CONDENSED  IS1ILK 


MILK  POWDER 


0.  F.  HUNZIKER 


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TO    THE 

MEMORY 

OF 

MY      FATHER 

THIS    VOLUME    IS    DEDICATED 


COPYRIGHT.    1914 
O.    F.    HUNZIKER 


ERRATA-   ^^^^  ^^^'  ^'Sure  57,  "The  Passburg  Milk   Dryer"  should 
^^  •  read  "The  Buflovak  Milk  Dryer." 
Page  195:  "The  Machine  used  was  of  the  Passburg  type"  should  read  "The 
Machine  used  was  of  the  Buflovak  type." 


CONDENSED  MILK  AND  MILK  POWDER 


Prepared  for  the  use  of 

Milk  Gondenseries,  Dairy  Students 
and  Pure  Food  Departments 


OTTO  F.  HUNZIKER,  B.  S.  A,  M.  S.  A. 

Professor  of  Dairy  Hnsbandry,  Pnrdne  Univershy 

and 

Chief  of  the  Dairy  Department  of  the 

Indiana  Agricnitnral  Experiment  Station 

LaFayette,  Indiana 

U.  S.  A. 


Poblished  by  the  Author 

LaFayette,  Indiana 

1914 


PREFACE 

This  book  treats  of  the  various  phases  of  the  condensed  milk 
and  powdered  niiilk  industry.  It  discusses  every  step  in  the 
process  of  manufacture,  following  the  milk  from  the  farmer's  door 
to  the  finished  product  in  the  pantry  of  the  consumer.  The  processes 
of  condensing  and  desiccating  milk,  skim  milk,  buttermilk  and  whey 
are  given  special  attention  and  the  defects  of  the  product,  their 
causes  and  prevention  are  explained  in  detail. 

The  inception  of  this  publication  is  the  result  of  innumerable 
and  persistent  calls  for  definite  and  reliable  information  on  the  sub- 
ject of  condensed  milk  and  milk  powder,  from  manufacturers  in  this 
country  and  in  foreign  lands ;  from  parties  contemplating  embarking 
in  the  business ;  from  national  and  state  experiment  stations  which 
are  oftentimes  called  upon  to  investigate  condiensed  milk  defects; 
from  d^iry  schools  desiring  to  give  instruction  on  the  subject ;  from 
national  and  state  pure  food  departments,  seeking  information  con- 
cerning the  possibilities  and  limitations  of  manufacture,  in  their 
efforts  to  formulate  and  enforce  standards  and  laws ;  and  from  com- 
me*-cial  chemists  in  need  of  reliable  methods  of  analyses  of  these 
jial  dairy  products. 

The  information  contained  in  this  volume  represents  the 
author's  experience,  covering  a  period  of  twelve  years,  in  the  prac- 
^■-il  manufacture  of  condensed  milk,  as  expert  advisor  to  milk 
».  ndensing  concerns  in  the  Unitedi  States,  Canada  and  Australia, 
and  as  visitor  of  condensed  milk  and  milk  powder  factories  in  this 
country  and  in  Europe. 

It  is  the  author's  hope  that  the  information  contained  herein 
may  serve  as  a  guide  to  manufacturers,  investigators,  teachers  and 
food  authorities.,  alike;  that  it  may  assist  in  a  better  understanding 
and  wider  dissemination  of  the  principles,  phenomena  and  facts 
involved  in  the  processes  of  manufacture;  and  that  it  may  lift  the 
obstructing  veil  of  unnecessary  secrecy  which  has  hovered  over 
these  industries  since  their  beginning,  curtailing  their  development 
and  depriving  them  of  much  of  the  light  of  advanced  science  to 
which  they  are  justly  entitled  and  which  they  need  for  their  greatest 
development  for  the  lasting  benefit  of  the  producer,  manufa(^turer 
and  consumer  alike. 

O.    F.    HUNZIKER. 

Purdue  University,  March,  1914. 


Condensed  Milk  and  Miek  Powder 
CONTENTS 


PART  I 

CONDENSED  MILK 

Chapter  I 
Definition 

History  and  Development  of  Industry — Invention  of  process;  develop- 
ment of  industry;  output  of  condensed  milk  in  the  United  States. 

Pages    1-16 

Chapter  II 

Essentials  of  Suitable  Locations  for  Milk  Condensing  Factories — Milk 
supply;  water  supply;  transportation  facilities;  other  conditions. 

Building  and  Equipment — Material  of  construction;  drainage;  general 
plan  of  factory;  list  of  equipment;  economic  arrangement  of  machin- 
ery;   sanitary  arrangement  of  machinery Pages  16-27 

Chapter  III 

Milk  Supply — Basis  of  buying  milk;  quality;  control  of  quality;  inspec- 
tion of  milk  at  the  condensery;  tests  for  purity  of  milk. 

Factory  Sanitation — Effect  on  patrons;  effect  on  wholesomeness  of 
product;  effect  on  marketable  property  of  product;  how  to  keep  fac- 
tory in  sanitary  condition   Pages  27-36 


PART  II 

MANUFACTURE   OF   SWEETENED   CONDENSED   MILK 

Chapter  IV 
Definition 
Heating — Purpose;  temperature;  manner;   advantages  and  disadvantages 

of  different  methods. 
Addition  of  Sugar — Kinds;  quality;  amount;  mixing  the  sugar.  Pages  37-45 

Chapter  V 

Condensing — Description  of  the  vacuum  pan. 

The  Condenser — Surface  condenser;  barometric  condenser;  wet-vacuum 
spray  condenser;  care  of  the  condenser. 

The  Expansion  Tank,  Catch-AU,  or  Milk  Trap. 

The  Vacuum  Pump. 

Science  and  Practice  of  Condensing  in  Vacuo — Object;  relation  of  pres- 
sure to  boiling  point;  relation  of  altitude  to  atmospheric  pressure; 
relation  of  steam  pressure  in  jacket  and  coils,  water  in  condenser, 
temperature  in  pan,  and  vacuum,  to  rapidity  of  evaporation. 

Starting  the  Pan. 

Operating  the  Pan. 

Prevention  of  Accidents  Pages  45-66 

IPWW^^ry  OF 
KlECOllEGEllBRARt 


II  Condensed  Milk  and  Milk  Powder 

Chapter  VI 

Striking  or  Finisliing  the  Batch — Definition;  ratio  of  concentration;  meth- 
ods of  striking. 

Use  of  the  Beaume  hydrometer;    correction  of  Beaume  reading  for 
temperature  variations;   specific  gravity  of  sweetened  condensed 
milk  of  different  Beaume  degrees;    sampling  the  batch. 
Drawing  off  the  condensed  milk. 
Cooling  the  Condensed  Milk Pages  66-73 

Chapter  VII 

Filling —  Filling  in  barrels;   filling  In  cans. 

Sealing — Kinds  of  seals;  soldering  devices  and  machinery;  solder:  solder- 
ing flux;  gas  supply,  gas  generators Pages  73-80 


PART  III 

MANUFACTURE  OF  UNSWEETENED  CONDENJSED  MILK 

EVAPORATED  MILK 

Chapter  VIII 
Definition. 

Quality  of  Fresh  Milk. 
Heating  the  Milk    Pages    80-83 

Chapter  IX 

Condensing. 

Striking — Use  of  the  Beaume  hydrometer;  correction  of  Beaume  reading 
at  temperatures  other  than  60°F;  calculation  of  specific  gravity  from 
Beaume  reading    Pages  83-86 

Chapter  X 

Homogenizing — Purpose;  principle  of  the  homogenizer;  kinds  of  homo- 
genizers;  operation  of  the  homogenizer;  effect  on  casein.  .Pages  86-89 

Chapter  XI 
Cooling. 

Filling,  Filling  Machines. 
Sealing,  Sealing  Machines  Pages  89-93 

Chapter  XII 

Sterilizing — Purpose  of  sterilization;    sterilizers;    loading  the  sterilizer; 

uniform   distribution   of   heat;    temperature   and   time   of   exposure; 

qualifications   of   processor;    rapid   and   uniform   cooling;    fractional 

sterilization. 
Shaking — Methods  of  shaking;  speed  of  the  shaker;  efficiency  of  different 

types  of  shakers;  formation  of  curd  not  desirable  nor  necessary. 
Incubating Pages  93-100 


Condensed  Miek  and  Miek  Powder  III 

Chapter  XIII 

Plain  Condensed  Bulk  Milk — Definition;  quality  of  fresh  milk;  heating 
of  fresh  milk;  condensing;  superheating;  striking;  ratio  of  concen- 
tration ;    cooling    , Pages   100-102 

Chapter  XIV 

Concentrated  Milk — Definition;  apparatus  needed;  operation  of  Camp- 
bell Process;   advantages  and  disadvantages  of  Campbell  process. 

Pages  102-104 

Chapter  XV 

Condensed    Buttermilk — Manufacture;    chemical    composition;    uses. 
Condensed  Whey,  Myseost,  or  Primost Pages  104-106 


PART  IV 
FROM    FACTORY   TO   CONSUMER 

Chapter  XVI 
Stamping. 
Inspecting — Checking  the  work  of  the  sealers;  disposition  of  leaky  cans; 

importance  of  inspection. 
Labeling — Labeling  machines;    principle  of  labeling  machines;    wrinkles 

and  rust  spots  on  labels. 
Packing — Marking  the  cases;  packing  condensed  milk  for  export. 

Pages  107-112 

Chapter  XVII 

Storage — Purpose  of  storing;   effect  of  storage  temperature;   advisability 

of  storing. 
Transportation    .Pages  112-115 

Chapter  XVIII 

Markets — Market  prices  of  condensed  milk;   exports  and  imports. 

Pages  115-119 
Chapter  XIX 

Chemical  Composition  of  Condensed   Milk — Sweetened  condensed   milk; 
evaporated  milk;   plain  condensed  bulk  milk;   concentrated  milk. 

Pages  119-127 

Chapter  XX 

Sanitary  Purity  and  Dietetic  Value  of  Condensed  Milk Pages  127-132 

Chapter  XXI 

Condensed  Milk  Standards  and  Laws — Federal  standards  for:   Sweetened 
condensed  milk;    evaporated  milk. 

Modified  standard;  difficulties  of  meeting  standard;  putting  composi- 
tion of  evaporated  milk  on  label. 
Condensed  Skim  Milk  Pages  132-136 


rV  Condensed  Milk  and  Milk  Powder 

Chapter  XXII 

Cost  of  Manufacture — General  Discussion. 

Cost  of  sweetened  condensed  milk  per  case. 

Cost  of  evaporated  milk  per  case Pages  136-139 


PART  V 

CONDENSED   MILK    DEFECTS,  THEIR  CAUSES   AND    PREVENTIONS 

Chapter  XXIII 
Classification  of  Defects. 
Defective  Sweetened  Condensed  Milk— Sandy,  rough  or  gritty;    settled; 

thickened  and  cheesy;   lumpy;   blown  or  fermented;   rancid;   putrid; 

brown   Pages  141-164 

Chapter  XXIV 

Defective  Evaporated  Milk  and  Plain  Condensed  Bulk  Milk — Curdy; 
grainy;  separated  and  churned;  fermented,  acid  curd,  bitter  curd, 
gassy  fermentation. 

Swelled  cans  due  to  freezing;   swelled  cans  due  to  chemical  action; 
brown;    gritty    Pages   164-177 

Chapter  XXV 

Adulterations  of  Condensed  Milk — Skimming;  addition  of  artificial  fats; 
addition  of  commercial  glucose;  addition  of  bi-carbonate  of  soda,  am- 
monium hydroxide,  lime  water  and  other  alkali;  addition  of  cream 
of  tartar ;   addition  of  starch Pages  177-180 


PART  VI 

MANUFACTURE   OF    MILK    POWDER 

Chapter  XXVI 
Definition. 
Kinds. 

History  and  Development  of  Industry. 
Quality  of  Fresh  Milk. 
Description    of    Principal    Processes;    Wimmer    process;    Just-Hatmaker 

process;    Eckenburg  process;    Passburg  process;    Campbell  process; 

Merrell-Gere  process  Pages  181-190 

Chapter  XXVII 
Packing  for  Market. 
Composition. 

Defects  of  Milk  Powders— High  water  content;   insoluble  milk  powders; 
non-miscible  milk  powders;  rancid  milk  powders. 

Markets   Pages  191-194 

Chapter  XXVIII 

Dried    Buttermilk    and    Dried    Whey— Manufacture    of;    composition    of 
buttermilk  powders   Pages  194-197 


Condensed  Milk  and  Milk  Powder 


PART  VII 

TESTS  AND   ANALYSES  OF   MILK,   CONDENSED   MILK   AND 
MILK  POWDERS 

Chapter  XXIX 

Practical  Methods  of  Systematic  Examination  of  Product  for  Marketable 
Properties — Number  of  samples  needed;  frequency  of  examination; 
technique  of  examination;  interpretation  of  results;  systematic  ex- 
amination a  necessary  factor  of  economic  manufacture.  .Pages  197-200 

Chapter  XXX 

Chemical  Tests  and  Analyses — Milk — specific  gravity — total  solids — ash — 
total  nitrogen — casein  and  albumin — lactose — butter  fat. 
Sweetened    Condensed    Milk — Preparation   of    sample — specific    grav- 
ity— total    solids — ash — proteids — lactose — butter    fat — sucrose — milk 
solids. 

Evaporated  Milk — preparation  of  sample — specific  gravity — total  sol- 
ids— tables  showing  total  solids,  when  Beaume  reading  and  per  cent, 
fat  are  known — ash — proteids — lactose — butter  fat. 
Milk  Powders — total  solids — ash — proteids — lactose — sucrose — butter 
fat   Pages  200-224 

Chapter  XXXI 

Detection  of  Adulterants  and  Preservatives — Extraneous  water;  skim- 
ming; extraneous  water  and  skimming;  artificial  coloring;  sucrose 
of  lime;  lime;  gelatin;  formaldehyde;  boric  acid;  benzoic  acid;  sali- 
cylic acid;    hydrogen  peroxide    Pages  224-231 

Chapter  XXXII 
Bacteriological  Analysis. 
Table  Showing  Legal  Standards  of  Dairy  Products  by  States. Pages  231-233 


ACKNOWLEDGMENTS 


It  is  my  pleasure  to  express  my  high  appreciation  and  gratitude 
to  Messrs.  George  Spitzer,  Associate  in  Dairy  Chemistry,  and  W.  F. 
Epple,  Assistant  Dairy  Chemist,  Purdue  University  Agricultural  Ex- 
periment Station,  for  much  valuable  assistance  in  the  preparation  of 
the  chapter  on  "Chemical  Analysis" ;  to  Professors  E.  S.  Ferry, 
Chief  of  the  Department  of  Physics,  G.  A.  Young,  Chief  of  the  De- 
partment of  Mechanical  Engineering,  and  Mr.  Arthur  Dufty,  Super- 
intendent of  Buildings,  Purdue  University,  for  timely  suggestions  on 
the  scientific  reflation  to  the  subject  of  physics  and  mechanics ;  to 
Messrs.  Ed.  B.  Gage,  Superintendent  of  the  Missouri  Condensed 
Milk  Co.,  Kohoka,  Mo.,  Frank  A.  Page.  Manager  of  Hires  Con- 
densed Milk  Co.,  Lake  Odessa,  Mich.,  and  W.  T.  Wilson,  President 
of  the  Indiana  Condensed  Milk  Co.,  Sheridan,  Ind.,  for  valuable 
data  connected  with  practical  manufacture ;  to  Mr.  F.  F.  Taylor, 
President  of  Borden's  Condensed  Milk  Co.,  for  biographic  data 
relating  to  Gail  Borden  and  for  cuts  for  illustrations  of  Gail  Borden 
and  of  the  first  milk  condensing  factory  in  the  United  States;  to 
Miss  Nellie  Tracy,  Secretary  of  the  Purdue  Agricultural  Experi- 
ment Station,  for  most  valuable  services  in  proof-reading;  and  to 
the  following  manufacturers  of  machinery  and  supplies  related  to 
the  manufacture  of  condensed  milk  and  milk  powder,  for  valuable 
cuts  for  illustration  in  the  text  and  for  their  generous  contributions 
of  advertisements  as  shown  at  the  conclusion  of  this  volume,  whose 
kindly  and  active  cooperation  made  possible  the  issuance  of  this 
publication :  American  Can  Co.,  A.  H.  Barber  Creamery  Supply 
Co.,  Bausch  and  Lomb  Optical  Co.,  Bessire  and  Co.,  Burt  Machine 
Co.,  Dairy  Machinery  and  Construction  Co.,  DeLaval  Separator  Co., 
F.  G.  Dickerson,  Eimer  and  Amend,  J.  B.  Ford  and  Co.,  Emil 
Greiner  Co.,  William  Grelck,  Arthur  Harris  and  Co.,  F.  K.  Higbie 
Co.,  Howe  Scale  Co.,  Ernst  Leitz,  Louis  F.  Nafis,  E.  H.  Sargent 
and  Co.,  Schaefer  Manufacturing  Co.,  Spencer  Lens  Co.,  Sprague 
Canning  Machinery  Co.,  Stevenson  Company,  Herman  Stier  Manu- 
facturing and  Engineering  Co.,  Sturges  and  Burn  Alanufacturing 
Co.,  C.  J.  Tagliabue  Manufacturing  Co.,  Taylor  Instrument  Co., 
The  Engineering  Co.,  The  Preservaline  ^Manufacturing  Co.,  The 
Torsion  Balance  Co.,  Union  Fibre  Co.,  and  Wagner  Glass  Works. 


Dairy  Building 

Purdue    University 

LaFayette,  Indiana 


The  dairy  school  is  the  manufactory  of  dairy 

knowledge,   the   clearing  house   of  dairy 

thought,  and  the  distributory  of  the 

dairy  gospel. — Hunziker. 


PART  I 

CONDENSED  MILK 

CHAPTER  I 
DEFINITION 

Condensed  milk  is  cow's  fresh  milk  from  which  a  considerable 
portion  of  the  water  has  been  evaporated  and  to  which  sucrose  may- 
or may  not  have  'been  added. 

There  are  chiefly  two  classes  of  condensed  milk,  namely,  sweet- 
ened and  unsweetened.  Both  reach  the  market  in  hermetically 
sealed  tin  cans  intended  for  direct  consumption,  and  in  bulk,  in- 
tended for  bakers,  confectioners  and  ice  cream  manufacturers. 

A  portion  of  the  condensed  milk  on  the  market  is  made  from 
the  chief  by-products  of  milk,  skim  milk  and  buttermilk.  Condensed 
skim  milk  supplies  the  same  markets  as  condensed  whole  milk  sold 
in  bulk.  Condensed  buttermilk  furnishes  a  valuable  chicken  feed. 
It  has,  also,  been  recommended  for  medicinal  purposes. 

HISTORY  AND  DEVELOPMENT  OF  INDUSTRY 

Invention  of  Process. — Condensed  milk  is  the  child  of  the 
nineteenth  century.  Its  origin  does  not  date  back  far,  and  its 
innovation  and  rapid  development  stand  in  sharp  contrast  to  those  of 
the  manufacture  of  butter  and  cheese,  industries  to  which  reference 
is  made  in  the  Old  Testament^  and  the  evolution  of  which  has  been 
very  gradual.  Notwithstanding  the  newness  of  this  product,  its 
manufacture  has  assumed  such  proportions  that  today  it  occupies  a 
prominent  place  among  the  leading  branches  of  dairy  manufactures. 

The  condensed  milk  industry  was  introduced  at  about  the  same 
time  as  the  factory  system  of  the  butter  and  cheese  industry ;  al- 
though, for  many  years  before  the  invention  of  a  successful  process 
of  condensing  milk,  methods  had  been  sought  to  preserve  milk. 

1  Book  of  Genesis,  C.  18,  V.  8:  "And  he  took  butter  and  milk  and  the  calf  he  had 
dressed  and  set  it  before  them" 

Book  of  Job,  C.  10,  V.  10:  "Hast  thou  not  poured  me  but  hke  milk  and  curdled  me 
like  cheese" 


10  Condensed  Milk  and  Milk  Powder 

The  American,  Gail  Borden,  the  inventor  of  the  mannfacture 
of  condensed  milk,  is  said  to  have  experimented  some  ten  years 
before  he  finally  decided  that  a  semi-fluid  state,  produced  by  evap- 
oration in  vacuo,  was  the  best  form  of  preservation.  He  first 
applied  for  a  patent  in  1853,  but  it  was  not  until  three  years  later 
that  the  Patent  Office  appreciated  the  originality  and  value  of  his 


Tig.  2.     Gail  Borden 


claim  sufficiently  to  grant  him  a  patent.  In  August,  1856,  he  was 
awarded  a  patent  on  his  process  both  by  the  United  States  and  by 
England. 

In  his  application  Mr.  Borden  says  •} 

"I  am  aware  that  sugar,  and  various  extracts,  have  been  and 
are  now  concentrated  in  vacuo  under  a  low  degree  of  heat,  to  pre- 
vent discoloration  or  burning.  I  do  not  claim  concentrating  milk  in 
a  vacuum  pan  for  such  a  purpose,  my  object  being  to  exclude  the 


1  "A  Brief  Sketch  of  Gail  Borden"  by  S.  I/.  Goodale,  Secretary  Maine  State  Board  of 
Agriculture,  1872.— Courtesy  of  P.  P.  Taylor,  President  of  Borden's  Condensed  Milk 
Company 


CoNDENSKD  Milk  and  Milk  Powder  ii 

air  from  the  beginning  of  the  process  to  the  end,  to  prevent  incipient 
decomposition.    This  is  important  and  I  claim  the  discovery.'' 

The  claim,  United  States  Patent,  August,  1856,  is  in  the  fol- 
lowing words : 

"Producing  concentrated  sweet  milk  by  evaporation  in  vacuo, 
substantially  as  set  forth, — the  same  having  no  sugar  or  other 
foreign  matter  mixed  with  it." 

Since  the  introduction  of  the  process  of  milk  condensing,  in- 
vented and  patented  by  Borden,  numerous  modifications  of  the 
process,  as  well  as  entirely  different  processes,  have  been  invented 
in  this  country  and  abroad.  The  most  characteristic  among  these 
are:  condciisation  by  refrigeration,  by  centrifugal  force,  by  boiling 
under  atmospheric  pressure,  by  passing  hot  air  through  milk,  etc. 
None  of  these  new  processes  have  proved  commercially  satisfactory, 
with  the  result  that  the  principle  of  the  process,  originally  invented 
by  Gail  Borden,  and  which  consists  of  condensing  the  milk  in  vacuo 
to  a  semi-fluid  liquid,  is  still  made  use  of  in  the  manufacture  of  the 
great  bulk  of  condensed  milk  produced,  both  in  this  country  and 
abroad. 

While  the  claim  of  the  patent  granted  Gail  Borden  was  that  of 
"producing  concentrated  sweet  milk  by  evaporation  in  vacuo  without 
the  admixture  of  sugar  or  other  foreign  matter,''  records  show  that 
Gail  Borden  manufactured  sweetened  condensed  milk,  sold  under 
the  famous  Eagle  Brand  label  as  early  as  1856.  The  first  adver- 
tisement by  Borden  of  unsweetened  condensed  milk  was  recorded 
in  Leslie's  Weekly,  May  22,  1858.     It  reads  as  follows: 

"Borden's  Condensed  Milk.  Prepared  in  Litchfield  County, 
Conn.,  is  the  only  milk  ever  concentrated  without  the  admixture  of 
sugar  or  some  other  substance  and  remaining  easily,  soluble  in  water. 
It  is  simply  Fresh  Country  Milk,  from  which  the  water  is  nearly 
all  evaporated,  and  nothing  added.  The  Committee  of  the  Academy 
of  Medicine  recommend  it  as  'an  article,  that,  for  purity,  durability 
and  economy,  is  hitherto  unequalled  in  the  annals  of  the  milk  trade.' 

"One  quart,  by  the  addition  of  water,  makes  two  and  a  half 
quarts, — equal  of  cream,  five  quarts  rich  milk  and  seven  quarts 
good  milk. 

"For  sale  at  173  Canal  Street,  or  delivered  at  dwellings  in  New 
York  or  Brooklyn  at  25  cents  per  quart." 

Development  of  Industry.  —  The  beginning  was  small, 
the   process  crude    and    the    product    imperfect.     Not   until   the 


Condensed  Milk  and  Milk  Powder 


strenuous  years  of  the  War  of  Secession  did  the  value  and  useful- 
ness of  condensed  milk  as  a  com- 
modity become  fully  recognized. 
During  the  Civil  War  there  was  a 
great  demand  for  this  product  and 
from  that  time  on  the  industry 
grew  with  great  rapidity. 

The  first  factory  was  operated 
by    Gail    Borden    in    Wolcottville, 
Litchfield    county,    Connecticut,    in 
^  the   summer   of    1856,    but    disap- 

Fig.   3.     The   first   condensed   milk   pointed    in    uot    obtaining    means, 

factory  in  America,  Wolcottville,  Conn.  ,,  •  i-    i      j         a 

nothing  was  accomplished.  A  sec- 
ond attempt  was  made  at  Burrville, 
five  miles  distant,  in  1857,  ^Y  ^  company  consisting  of  the  owners  of 
the  patent.  A  small  quantity  of  milk  was  here  successfully  con- 
densed and  its  introduction  into  New  York  began.  Although 
admitted  by  all  to  be  superior  to  any  before  made,  it  was  slow  in 
meeting  with  sales  proportional  in  magnitude  to  the  expenses  in- 
curred. Yielding  to  the  monetary  revulsion  of  that  year  the  company 
suspended  operations,  leaving  Mr.  Borden  liable  for  bills  drawn,  on 
which  he  was  sued. 

It  was  not  until  February,  1858,  when  Mr.  Borden  (with  the 
other  owners  of  the  patent)  associated  himself  with  Jeremiah  Mil- 
bank,  Esq.,  who  advanced  money  to  revive  the  business,  that  he 
could  be  said  to  enjoy  adequate  means  to  develop  his  invention  and 
at  which  time  the  New  York  Condensed  Milk  Company  was 
formed.  Abandoning  Burrville,  the  new  company  established  work 
on  a-  more  extensive  scale  in  Wassaic,  Duchess  county,  New  York, 
in  i860.  In  1865,  extensive  works  were  erected  at  Elgin,  Illinois. 
Borden's  Condensed  Milk  factories  today  number  upwards  of  fifty, 
extending  from  Maine  to  Washington  State  as  well  as  into  Canada. 
The  New  York  Condensed  Milk  Company  was  incorporated  in  New 
Jersey  in  i860  and  in  New  York  in  1870.  This  company  was 
succeeded  by  Borden's  Condensed  Milk  Company  which  was  in- 
corporated in  New  Jersey  in  1899 

In  the  sixties  of  the  last  century,  the  Anglo-Swiss  Condensed 
Milk  Company  was  organized  in  Switzerland  under  the  leadership 
of  Charles  A.  Page,  then  United  States  Consul  at  Zurich,  Switzer- 


Condensed  Milk  and  Milk  Powder  13 

land,  and  his  brother  George  H.  Page,  and  with  the  assistance  of 
Swiss  and  English  capital.  The  first  factory  of  that  company  was 
built  and  operated  in  1866  at  Cham,  Lake  Zug,  Switzerland,  under 
the  direction  of  George  H.  Page,  who  was  its  president  until  1898, 
when  he  died. 

This  company  prospered  and  grew  rapidly  in  Europe.  In  the 
eighties  of  the  last  century  it  invaded  the  United  States,  where  it 
built  and  operated  several  large  factories  in  New  York,  Wisconsin 
and  Illinois.  The  American  factories  were  managed  by  David  Page 
and  William  B.  Page,  brothers  of  George  H.  Page.  In  1902  the 
Anglo-Swiss  Condensed  Milk  Company  sold  its  entire  American 
interests,  factories  and  business,  to  Borden's  Condensed  Milk  Com- 
pany. In  1904  the  Anglo-Swiss  Condensed  Milk  Company  consoli- 
dated with  Henry  Nestle,  of  Vevay,  Lake  Geneva,  Switzerland,  an- 
other successful  manufacturer  of  condensed  milk.  The  company 
which  is  now  known  as  the  Nestle-Cham  Condensed  Milk  Company, 
is  operating  some  twenty  large  condensed  milk  factories  in  European 
countries,  with  headquarters  at  Cham,  Switzerland. 

Up  to  the  early  eighties  of  the  last  century,  sweetened  con- 
densed milk  was  the  only  condensed  milk  that  was  put  on  the  mar- 
ket and  sold  in  hermetically  sealed  cans,  while  unsweetened  con- 
densed milk  was  manufactured  and  sold  open,  largely  direct  to  the 
consumer,  in  a  similar  way  as  market  milk.  The  purity  and  keeping 
quality  of  this  unsweetened  condensed  milk,  however,  were  greatly 
superior  to  market  milk. 

In  1885  the  Helvetia  Milk  Condensing  Company  was  organized 
and  started  operation  at  Highland.  Illinois,  under  the  direction  of 
Messrs.  Latzer,  John  Wildi  and  others  of  Swiss  birth.  This  com- 
pany confined  its  efforts  exclusively  to  the  manufacture  of  evap- 
orated milk  (unsweetened  condensed  milk,  sold  in  hermetically 
sealed  cans).  After  several  unsuccessful  attempts,  they  finally  suc- 
ceeded in  putting  on  the  market  a  sterilized,  unsweetened  condensed 
milk.  At  first  this  unsweetened  condensed  milk  failed  to  appeal  to 
the  public;  but  of  late  years  the  demand  for,  and  the  manufacture 
of  this  product  have  increased  very  rapidly,  so  that  today,  in  this 
country,  the  output  of  evaporated  milk  exceeds  that  of  sweetened 
condensed  milk.  Originally  this  unsweetened  condensed  milk  was 
labelled  and  sold  under  the  name  of  "Evaporated  Cream."     The 


u 


CoNDENSKD  Milk  and  Milk  Powder 


Federal  Food  and  Drugs  Act  of  1906  caused  the  name  "evaporated 
cream"  to  be  changed  to  "evaporated  milk." 

In  this  country,  as  well  as  in  Canada  and  Europe,  the  condensed 
milk  industry  grew  rapidly.  Every  succeeding  decade  marked  the 
organization  of  new  companies  and  the  erection  of  new  factories 
until  today,  there  are  milk  condensing  factories  in  nearly  every 
civilized  country  within  the  dairy  belt. 

Output  of  Condensed  Milk  in  the  United  States. — In  the  last 
ten  years,  from  1899  to  1909.  the  output  of  condensed  milk  in  the 
United  States  nearly  trebled,  as  shown  by  the  United  States  Census 
figures  recorded  below. 

United  States  Census  Report,  1910 


Output  of  condensed  milk 
in  the  United  States 

1899 

1904 

1909 

Condensed  milk,  total 

Amount,  pounds 
Value,    dollars 

186,921,787 
11,888,792 

308,485,182 

20,149,282 

494,796,544 
33,563,129 

Sweetened — 

Amount,  pounds 
Value,  dollars 

(I) 
(I) 

198,355,189 
13,478,376 

214,518,310 
17,345,278 

Unsweetened — • 

Amount,  pounds 
Value,  dollars 

(I) 

(0 

110,129.993 
6,670,906 

280.278,234 
16,217,851 

1  Not  reported  separately 

The  above  figures  show  that  the  total  output  of  condensed  milk 
in  this  country  in  1909  was  494,796,544  pounds,  estimated  at  a  value 
of  $33,653,129.  Calculating  the  ratio  of  concentration  at  2.  5  :  i, 
which  is  liberal,  the  total  amount  of  fluid  milk  supplying  our  con- 
denseries  in  1909  amounted  to  over  one  billion  pounds.  The  above 
figures  largely  represent  the  canned  goods  only.  Within  recent 
years  the  manufacture  of  condensed  milk  in  bulk,  especially  for  the 
ice  cream  trade,  has  increased  enormously,  so  that,  if  this  bulk  milk 


Condensed  Milk  and  Milk  Powder  15 

were  included  in  the  above  figures,  the  estimate  of  the  total  output 
would  be  materially  increased. 

In  1899,  there  were  in  operation  in  this  country  about  fifty 
factories  manufacturing  condensed  milk,  distributed  over  fourteen 
dififerent  states,  New  York  and  Illinois  leading  the  list  by  over  50 
per  cent.  In  1904,  the  Government  estimated  the  total  number  of 
condenseries  in  operation  at  eighty-seven.  Today  there  are  in  the 
United  States  over  two  hundred  milk  condensing  factories,  dis- 
tributed over  twenty-three  different  states  as  shown  below.. 

Distribution  of  Milk  Condensing  Factories  in  United  States 
States  Number  of  Factories 


Arizona 
California 


7 


Colorado  i 

Illinois  39 

Indiana  9 

Iowa  3 

Kansas  4 

Kentucky  i 

Maine  i 

Maryland  3 

Massachusetts  i 

]\Iichigan  12 

Missouri  2 

New  Jersey  6 


New  York 


54 


North  Dakota  i 

Ohio  10 

Oregon  6 

Pennsylvania  20 

Utah  6 

\^ermont  4 

Washington  14 

Wisconsin  26 


Total  23  240 


i6  Condensed  Milk  and  Milk  Powder 

Other  countries  in  which  the  condensed  milk  industry  has  made 
rapid  progress  are:  Canada,  Australia,  New  Zealand,  Switzerland, 
Germany,  England,  Ireland,  Holland,  Sweden,  Norway,  Austria, 
Russia,  Japan  and  India. 

CHAPTER  II 

ESSENTIALS  OF  SUITABLE  LOCATIONS  FOR  MILK 
CONDENSING  FACTORIES 

Unlike  the  establishment  of  creameries  and  cheese  factories,  the 
building  of  condenseries  and  the  installing  of  the  necessary  ma- 
chinery involve  the  investment  of  large  capital.  There  is  need  of 
a  substantial  building  and  of  expensive  machinery.  The  supplies 
are  numerous  and  must  be  purchased  in  larger  quantities  be- 
fore the  returns  from  the  sale  of  the  manufactured  product  are 
available.  It  is  estimated  that  it  takes  from  three  to  six  months 
before  the  condensed  milk  reaches  the  consumer.  This  holds  true 
especially  in  the  case  of  canned  goods.  The  fixed  expenses  also, 
are  comparatively  heavy,  and  do  not  materially  change  with  a  de- 
crease or  increase  in  the  milk  supply. 

All  of  these  facts  emphasize  the  importance  of  locating  the  fac- 
tory in  a  territory  most  suitable  for  economic  manufacture,  to  guard 
against  heavy  loss  which  would  naturally  result  in  localities  unfav- 
orable to  the  industry. 

The  chief  factors  to  be  considered  in  this  connection  are 

Milk  supply 

Water  supply 

Transportation  facilities 

Other  conditions 

Milk  Supply. — A  large  supply  of  milk  with  possibilities  for 
extending  the  milk  supply  territory  is  the  first  essential.  The  con- 
densery  must  have  milk  to  do  business.  The  locality  in  which  it  is 
located  must  be  adapted  for  the  production  of  large  quantities  of 
milk ;  it  must  be  a  dairy  country  where  reasonably  large  herds  are 
kept.  Other  things  being  equal,  the  larger  the  milk  supply,  the  low- 
er the  cost  of  manufacture.  Where  the  milk  supply  drops  below 
fifteen  thousand  pounds  of  milk  daily,  profitable  manufacture  be- 
comes difficult.     Territories  of  gathered  cream  creameries  are  us- 


Condensed  Milk  and  Milk  Powder  17 

ually  not  very  desirable.  The  farmers  generally  have  small  herds 
and  are  not  inclined  to  haul  their  milk  daily.  They  prefer  to  take 
their  cream  to  the  creamery  once  or  twice  per  week,  or  whenever  it 
is  convenient  for  them  to  do  so.  Again,  they  appreciate  the  feed- 
ing value  of  the  skim  milk,  and  depend  on  the  skim  milk  to  raise 
their  young  stock  and  pigs.  When  they  take  their  milk  to  the  con- 
densery,  there  is  no  skim  milk  nor  buttermilk  left  for  feeding  pur- 
poses. 

The  presence  of  whole  milk  creameries  and  cheese  factories 
does  not  disqualify  a  locality  for  milk  condensing.  On  the  con- 
trary, it  is  a  strong  point  in  favor  of  a  condensery  site.  The  farm- 
ers usually  have  reasonably  large  herds,  they  are  accustomed  to 
take  reasonable  care  of  their  milk  and  to  haul  it  to  the  factory 
daily,  and  the  condensery  prices  are  generally  high  enough  above 
the  creamery  or  cheese  factory  prices  to  induce  the  farmers  to  pa- 
tronize the  condensing  factory. 

Territories  in  close  proximity  of  large  consuming  centers, 
though  dairying  may  have  reached  a  high  state  of  development,  are 
not  desirable,  owing  to  the  continuous  and  growing  demand  for 
fresh  milk.  Competition  of  this  kind  means  high  prices,  which  no 
business  tactics  are  capable  of  modifying. 

Water  Supply. — The  value  to  the  milk  condensing  plant  of  a 
generous  and  never-failing  supply  of  clean,  cool  water  cannot  be 
over-estimated.  The  folly  of  erecting  condenseries  without  first 
ascertaining  the  water  supply  has  frequently  compelled  milk  con- 
densing companies  to  abandon  new  plants,  merely  because  of  lack 
of  water. 

In  addition  to  the  water  used  in  the  boilers  and  for  washing 
purposes,  large  amounts  of  water  are  necessary  for  condensing  and 
for  cooling  the  condensed  milk.  It  is  estimated  that  the  condensa- 
tion of  one  pound  of  fresh  milk  requires  about  three  gjillons  of 
water. 

The  water  must  be  pure.  In  spite  of  all  precautions,  it  will 
come  in  contact,  more  or  less,  with  the  milk.  Though  all  apparatus 
and  utensils  holding  and  conveying  milk  and  condensed  milk  may 
be  thoroughly  steamed  after  rinsing  with  water,  there  are  untold 
channels  through  which  the  milk  may  become  contaminated  with 


i8  Condensed  AIilk  and  Milk  Powder 

polluted  water.  Frequently,  while  the  milk  is  condensing,  the  vac- 
uum pump  accidentally  stops.  If  the  processer  fails  to  immediately 
shut  off  the  water  supplying  the  condenser,  water  will  pour  back 
from  the  condenser  into  the  milk  in  the  vacuum  pan.  In  the  case 
of  filthy,  polluted  water,  the  entire  batch  may  be  ruined.  Again, 
the  pan  is  usually  rinsed  between  batches,  and,  if  the  water  used  is 
unclean,  it  will  contaminate  the  milk  of  the  succeeding  batch.  Fin- 
ally, when  the  heavy  40-quart  cans  filled  with  condensed  milk  are 
set  into  the  cooling  tank,  water  frequently  splashes  over  into  the 
cans.  Here  again,  the  quality  of  the  condensed  milk  is  jeopardized, 
imless  the  water  used  is  pure. 

The  water  must  be  cold.  The  colder  the  water,  the  more  sat- 
isfactory is  the  operation  of  the  vacuum  pan.  If  the  temperature 
of  the  water  used  in  the  condenser  rises  much  above  65  degrees  F. 
the  process  of  condensing  becomes  difficult.  Cold  water  is  essential, 
also,  for  the  prompt  and  proper  cooling  of  the  unsweetened  con- 
densed milk. 

Transportation  Facilities. — It  is  essential  that  the  factory  have 
access  to  one  or  more  railway  lines. 

While,  for  reasons  discussed  under  "Milk  Supply,"  it  is  not 
advisable  to  erect  a  factory  in  too  close  proximity  to  large  consum- 
ing or  railway  centers,  it  is  equally  undesirable  to  choose  a  conden- 
sery  site  where  transportation  facilities  are  poor. 

Where  access  to  one  railroad  only  can  be  had.  the  factory  is 
at  the  mercy  of  that  road.  Experience  has  shown  that  monopoly 
of  transportation  usually  means  a  low  standard  of  efficiency  of 
service  and  high  freight  rates.  On  the  other  hand,  competition  in- 
volves a  struggle  for  the  survival  of  the  fittest,  and  it  offers  the 
public  all  the  inducements  that  business  ingenuity  and  enterprise 
can  produce.  Where  two  or  more  transportation  companies  are 
after  the  business  of  the  same  manufacturing  concern,  they  will 
generally  leave  nothing  undone  in  the  way  of  accommodations  and 
low  rates  to  please  the  manufacturer.  The  result  is  that  the  man- 
ufacturer enjoys  the  advantages  of  efficient  service,  good  accom- 
modations and  reasonable  freight  rates. 


Condensed  Milk  and  Milk  Powder  19 

This  is  a  factor  which  the  condensery  cannot  afford  to  over- 
look, as  the  freight  charges  are  a  very  conspicuous  item  in  the  ex- 
pense account  of  the  milk  condensing  business.  A  part  of  the 
fresh  milk  may  have  to  be  shipped  to  the  factory  by  rail,  all  the 
finished  product  must  leave  the  factory  by  rail  and  the  condensery 
is  dependent  on  the  railway  for  its  raw  materials  and  supplies,  such 
as  sugar,  tinplate,  solder,  box  shooks,  barrels,  labels,  oil,  rosin,  gas- 
oline, coal,  etc.  Prompt  and  efficient  transportation  is  essential. 
Undue  delays  may  cause  the  condensery  serious  inconvenience  and 
loss,  and  may  result  in  the  cancelling  of  important  orders. 

Other  Conditions. — The  removal  of  the  sewage  of  the  factory 
is  important.  It  may  be  possible  for  the  factory  to  connect  with 
the  town  or  city  sewer,  in  which  case  the  problem  is  easily  solved. 
Where  this  is  not  possible,  a  site  along  a  creek,  river,  pond  or  lake 
may  offer  effective  means  to  take  care  of  the  condensery  sewage. 
Where  no  such  natural  depository  is  available,  the  elevation  of  the 
site  should  be  sufficient  to  carry  off  the  sewage  far  enough  from 
the  factory  to  insure  the  plant  against  foul  odors  and  unsanitary 
conditions.  In  the  absence  of  all  of  these  avenues  for  the  disposal 
of  the  sewage,  a  properly  laid-out  system  of  septic  tanks  with  effi- 
cient filter  beds  may  serve  the  purpose. 

Where  possible,  it  is  advisable  to  take  advantage  of  hillsides, 
affording  natural  means  to  arrange  and  operate  the  factory  on  the 
gravity  plan. 

BUILDING  AND  EQUIPMENT 

Material  of  Construction. — vSince  the  establishment  of  a  milk 
condensing  factory  involves  the  investment  of  considerable  capital, 
those  willing  to  invest  must  have  faith  in  the  permanency  of  the 
business.  For  a  permanent  business,  a  building  substantially  con- 
structed is  the  most  economical.  Most  of  the  factories  belonging  to 
the  most  reputable  concerns  are  built  very  substantially.  However, 
there  are  in  this  country  condensing  factories,  in  the  construction 
of  which,  cheapness  was  the  governing  factor.  Many  of  these  cheap 
factories  are  the  work  of  unscrupulous  promoters  whose  ambition 
it  is,  to  convince  men  of  wealth  or  farming  communities  of  the  "enor- 
mous" profits  possible  in  the  manufacture  of  condensed  milk,  and 
to  induce  them  to  invest  large  sums  of  money  in  the  condensed  milk 


20  Condensed  Miek  and  Milk  Powder 

industry.  By  skillful  manipulation  these  promoters  frequently 
secure  "fat  rake-oflfs"  on  every  purchase  of  machinery  and  on  every 
contract  of  labor.  Their  victims  pay  exorbitant  prices  for  a  first 
class  building  and  most  up-to-date  equipment,  and  often  receive  a 
shack  barely  strong  enough  to  stand  up  under  its  own  weight,  and 
equipment  of  inadequate  capacity. 

Stone,  brick  and  concrete,  according  to  availability,  are  most 
desirable  materials  of  which  to  construct  a  condensery.  In  the  case 
of  wooden  walls  or  partitions,  they  should  rest  on  cement,  brick  or 
stone,  built  up  at  least  two  feet  from  the  floor,  or  the  lower  two  feet 
of  such  walls  and  partitions  should  be  wainscoated  with  good  cem- 
ent plaster.  All  floors  of  the  main  building  should  be  of  cement, 
with  at  least  three  and  one-half  inches  of  concrete  on  a  good  foun- 
dation, and  one-half  to  three-fourths  inch  cement  surfacing.  If  the 
walls,  partitions  and  ceilings  are  of  wood,  they  should  be  lathed  and 
plastered  with  damp-proof  plaster  on  the  inside.  Matched  lumber  is 
unsatisfactory.  It  generally  soon  warps  and  peals  off,  owing  to 
exposure  to  free  steam  and  dampness.  Plenty  of  ventilators  should 
be  provided  in  the  boiler  room,  receiving  platform,  vat  room  and 
well  room  to  afford  a  ready  escape  of  steam  and  foul  air,  facilitate 
the  regulation  of  the  temperature  and  prevent  the  walls  and  ceil- 
ings from  "sweating." 

Drainage. — All  floors  of  the  manufacturing  rooms  should  slope 
to  facilitate  rapid  drainage.  A  fall  of  one-eighth  inch  per  foot 
is  usually  sufficient.  Large  water-sealed  floor  drains  should  be  suf- 
ficiently numerous  and  well  placed  in  all  rooms  to  rapidly  carry 
off  water.  The  surface  of  these  floor  drains  should  be  about  one- 
half  inch  below  that  of  the  adjoining  floor,  so  as  to  catch  the  water, 
readily.  In  the  larger  rooms  open  drain-ditches  in  the  cement  floor 
six  to  eight  inches  wide,  and  covered  with  perforated  iron  plates,  are 
preferable  to  bell-traps.  They  may  be  placed  along  the  walls  or 
elsewhere.  They  should  be  not  more  than  forty  feet  apart  and  have 
a  fall  of  one-eighth  inch  to  the  foot,  with  the  floor  sloping  toward 
them.  It  is  generally  most  convenient  to  have  all  the  drain  pipes 
enter  into  one  large  sewer  pipe  not  less  than  ten  inches  in  diameter, 
for  a  condensery  receiving  about  fifty  thousand  pounds  of  milk  daily, 
which  should  dispose  of  all  the  factory  sewerage. 


Condensed  Milk  and  Milk  Powder 


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22  '    Condensed  Milk  and  Milk  Powder 

General  Plan  of  Factory. — Most  of  the  condensing  factories 
are  either  one  or  two  story  buildings.  In  the  case  of  two-story 
buildings  the  first  floor  is  usually  devoted  to  the  boiler  and  engine 
rooms,  vat  room,  well  room,  filling,  sealing  and  packing  rooms.  On 
the  second  floor  are  installed  the  pan  room,  store  room  for  sugar 
and  box  shooks.  the  tinshop  and  possibly  the  offices.  A  basement 
is  sometimes  provided  and  used  for  the  storing  of  condensed  milk. 

Fig.  4  illustrates  a  floor  plan  of  a  milk  condensing  factory  with 
a  capacity  of  fifty  thousand  pounds  of  milk  daily.  All  operating 
rooms  are  located  on  one  floor.  The  arrangement  of  machinery 
permits  of  the  handling  of  the  milk  on  the  gravity  plan  or  with 
pumps,  according  to  the  topography  of  the  site  and  the  elevation  of 
the  rooms.  The  receiving  room  floor  and  the  platform  which  accom- 
modates the  vacuum  pans,  should  be  seven  to  eight  feet  above  the 
main  floor.  In  order  to  take  care  of  storage  of  water,  sugar,  tin 
cans,  barrels  and  box  shooks,  there  should  be  a  second  floor  over 
the  well  room  and  the  filling,  sealing  and  sterilizing  room.  The 
ceiling  of  these  rooms  should  be  not  less  than  sixteen  feet  above 
the  floor. 

The  rooms  are  so  arranged  as  to  necessitate  the  minimum  ex- 
penditure of  machinery,  conveyors  and  labor.  All  work  rooms  open 
on  the  railway  switch,  and  the  storage  room  is  accessible  by  two 
elevators.  The  well  room,  where  most  of  the  steam  is  needed,  is 
next  to  the  boiler  room,  so  as  to  minimize  condensation  in  the  steam 
pipes.  If  the  main  steam  pipes  are  properly  insulated,  this  arrange- 
ment should  furnish  the  vacuum  pans  with  dry  steam.  The  floor 
in  the  boiler  room  should  be  two  feet  below  the  main  floor,  in  order 
to  give  additional  fall  for  the  condensation  water  from  jacket  and 
coils  of  the  vacuum  pans  to  the  boiler  feed  tank. 

The  partition  between  the  receiving  room  and  testing  room  is 
equipped  with  a  cabinet,  opening  on  both  sides  so  that  the  sample 
bottles  can  be  placed  on  the  shelves  in  the  receiving  room,  and  taken 
ofif  the  shelves  in  the  test  room. 

From  the  weigh  cans  on  the  receiving  platform  the  milk  runs 
direct  into  the  hot  wells,  which  are  sufficient  in  number  to  conven- 
iently divide  the  milk  into  batches  and  to  heat  the  milk  with  the 
least  possible  delay.  The  capacity  of  the  vacuum  pumps  is  aug- 
mented by  their  close  proximity  to  the  vacuum  pans  and  the  hot- 


Condensed  Milk  and  Milk  Powder  23 

wells  and  by  the  fact  that  the  water  supply  tanks  are  overhead. 
The  space  to  be  evacuated  is  confined  very  largely  to  the  vacuum 
pan  only,  the  milk  has  to  be  lifted  by  the  vacuum  pump  but  a  few 
feet  and  the  water  runs  into  the  condenser  by  gravity. 

From  the  well  room  the  condensed  milk  is  transferred  to  the 
tanks  on  the  platform  over  the  filling  machines.  The  evaporated 
milk  is  pumped  from  the  cooling  coils  through  the  wall  and  the 
sweetened  condensed  milk  is  raised  to  the  platform  in  ten  gallon 
cans  on  the  elevator.  The  sealing  benches  are  equipped  with  self- 
heating  soldering  coppers.  In  the  place  of  the  soldering  benches 
and  hand  coppers,  an  automatic  sealing  machine  may  be  installed. 
The  sterilizers  and  shakers  are  conveniently  placed  to  take  care  of 
the  sealed  evaporated  milk.  The  tin  cans  for  the  sealing  room  and 
the  box  shooks  for  the  packing  room  are  brought  down  from  the 
storage  room  overhead  on  the  elevator.  The  labeling  and  packing 
room,  equipped  with  the  labeling  and  box  nailing  machines,  pro- 
vides for  considerable  storage  of  the  fini.shed  product.  Additional 
storage  at  a  moderate  and  uniform  temperature  might  be  provided 
for  by  a  basement  under  the  packing  room.  A  label  stock  room 
furnishes  satisfactory  storage  for  the  labels. 

In  case  the  factory  manufactures  its  own  tin  cans,  a  tin  shop, 
equipped  with  the  necessary  machinery,  (see  list  of  machinery  and 
equipment)  should  be  located  in  as  close  and  convenient  proximity 
to  the  filling  and  sealing  room  as  possible.  A  suitable  place  is  di- 
rectly opposite  the  filling  room  with  the  railway  track  separating 
the  latter  from  the  tin  shop.  The  tin  shop  should  have  two  outside 
doors  and  its  machinery  .should  be  so  arranged  that  the  tin  plate 
can  be  unloaded  from  the  car  at  one  door,  is  moved  back  through 
the  machinery  and  appears  again  in  the  form  of  finished  cans  at 
the  other  door,  directly  opposite  the  filling  room  and  ready  for  the 
reception  of  the  condensed  milk.  Instead  of  erecting  a  separate 
building  for  the  tin  shop,  the  latter  may  also  be  conveniently  in- 
stalled in  the  second  story  directly  over  the  filling  room. 

Where  natural  gas  and  gas  from  municipal  corporations  is 
not  available  one  or  more  gasoline  gas  generators  .should  be  in- 
stalled. The.se  gas  generators  contain  inflammable  material  and 
should,  therefore,  be  located  at  a  reasonable  distance  from  the  main 
building. 


24  Condensed  Mii.k  and  Milk  Powder 

List  of  Equipment. — The  following  is  a  list  of  the  principal 
machinery  and  equipment  needed  in  an  up-to-date  condensery  with 
a  capacity  of  fifty  thousand  pounds  of  milk  daily : 

BOILER    ROOM 

Boilers  with  a  total  capacity  of  400  H.  P. 
I  boiler  feed  tank 
I  boiler  feed  pump 
I  boiler  water  heater 

ENGINE    ROOM 

1  40  H.  P.  engine 

2  well  pumps,  150  gallon  per  minute  each 

1  80  light  dynamo 

Pipe  and  thread  cutting  tools,  anvil  and  forge 

RECEIVING   ROOM 

2  1000  pound  weigh  cans,  "low  down"  style 
2  6  beam  milk  scales 

I  can  washing  machine  with  steam  and  water  jets   and 

air  blower  for  drying  the  cans 
I  milk  sample  bottle  rack 

WELL    ROOM 

6  5000  pound  capacity  jacketed  kettles  with  revolving  agi- 
tators and  superheating  device 
I  6  foot  vacuum  pan 

1  7  foot  vacuum  pan 

2  vacuum  pumps 

2  500  gallon  standardizing  vats 
I  6  cylinder  homogenizer 

1  internal  tube  cooler,  capacity  5000  to  8000  pounds  per 

hour 

2  36  can  cooling  vats  with  cans,  cross  bars  and  paddles, 

complete 
I  wash  tank 
I  elevator 
I  sugar  chute 


Condensed  Milk  and  Mii,k  Powder  25 

I  2  beam  platform  scale 
I  truck 


FILLING,   SEALING   AND   STERILIZING    ROOM 

4  200  gallon  condensed  and  evaporated  milk  vats 
2  filling  machines  for  sweetened  condensed  milk 
2  filling  machines  for  evaporated  milk 
4  soldering  benches,   5x20  feet,  with    10  self-heating  sol- 
dering coppers  each,  or 

1  or  more  sealing  machines,  the  number  depending  on  type 

and  capacity  of  machine  used 
2000  wooden  trays  holding  24  sixteen-ounce  cans  each 

2  sterilizers,  capacity  75  to  100  cases  each,  complete  with 

iron  trays 

1  double  shaker 

2  trucks 

LABELING  AND  PACKING  ROOM 
2  labeling  machines 
2  nailing  machines 
2  trucks 

TESTING    ROOM 

2  24-bottle   Babcock  testers,  with   one  gross  of   standard 
milk  test  bottles  and  accessories,  complete 
Equipment    for   chemical    and    bacteriological    analyses 
of  milk  and  sugar 

OFFICES 

Usual  equipment 

TOILET  ROOMS 

Usual  equipment 

OVERHEAD  STORAGE  ROOM 

I  50,000  gallon  water  tank 

This  tank  is  preferably  located  outside  of  factory 
I  4  beam  platform  scale  for  sugar 


26  CONDKNSKD  MiLK   AND  MiLK   PoWDER 

ADDITIONAL.   EQUIPMENT 

1  gasoline  gas  generator  (complete),  needed  in  absence  of 

access  to  natural  gas  or  municipal  gas 

TIN   SHOP 

Needed  in  case  cans  are  manufactured  at  the  factory 

2  squaring  shears 

2  body  cutting  machines 
2  lock  seamers 
6  presses 

2  crimping  machines 
2  soldering  floats 
I   can  tester  with  vacuum  pump 
I  can  wiper 
I  lathe  with  tools 
I  gasoline  gas  generator,  complete 
I  25  H.  P.  engine  or  motor 
200  can  crates 

Economic  Arrang-ement  of  Machinery. — In  the  arrangement 
and  connection  of  the  machinery,  economy  of  manufacture  and  san- 
itation of  the  product  shoidd  receive  serious  consideration.  The 
machinery  should  be  so  arranged  as  to  reduce  to  the  minimum  the 
space,  pumps,  pipes  and  conveyors  needed.  Pumps,  conveyors, 
pipes  and  fittings  are  expensive,  and  the  space  saved  by  judicious  ar- 
rangement of  the  stationary  machinery  may  be  used  to  advantage 
for  other  purposes. 

Human  muscle  is  the  most  expensive  form  of  motive  power. 
Wherever  muscle  can  be  replaced  by  machinery  and  where,  by  in- 
telligent arrangement  of  the  machinery,  unnecessary  steps  and  hand- 
ling can  be  avoided,  the  cost  of  manufacture  is  reduced. 

Sanitary  Arrangement  of  Machinery. — Milk  pumps,  milk 
pipes,  milk  troughs  and  other  milk  conveyors  are.  at  best,  enemies 
of  sanitation.  They  should  be  avoided  wherever  possible.  The 
gravity  system  of  conveying  milk -should  be  used  in  preference  to 
the  pumping  system.  Milk  pipes  should  be  short  and  accessible; 
all  vats  should  be  of  sanitary  construction ;  wooden  jackets  should 
not  be  tolerated ;  all  seams  in  the  vats  and  kettles  .should  be  well 


Condensed  Milk  and  jMilk  Powder  2J 

flushed  with  solder ;  milk  pumps  should  be  brass  lined ;  no  black  iron 
pipes  should  be  used  for  transferring  milk ;  all  milk  pipes  should 
be  of  galvanized  iron  or  copper,  heavily  tinned  over  on  the  inside ; 
long  lines  of  milk  pipes  should  be  equipped  with  unions  at  short 
distances ;  crosses  or  sanitary  couplings  should  be  used  in  place 
of  elbows,  in  order  to  render  all  sections  of  the  milk  pipes  easily 
accessible  to  flue  brushes. 

CHAPTER  III 
MILK  SUPPLY 

Basis  of  Buying  Milk. — The  prices  which  the  condensery  pays 
the  patrons  are  not  usually  governed  by  any  board  of  trade.  They 
do  not  even  necessarily  follow  the  quotations  of  the  butter  and 
cheese  market.  They  are  generally  announced  from  three  to  six 
months  in  advance.  They  average,  in  most  cases,  from  twenty  to 
fifty  cents  higher  per  hundred  pounds  of  milk  than  those  paid  by 
the  creameries  and  cheese  factories. 

Most  condenseries  pay  for  the  milk  on  the  one  hundred  pound 
basis.  Some  factories  are  still  clinging  to  the  Mediaeval  custom 
of  buying  milk  by  the  quart,  using  the  yard  stick  for  the  remnant 
cans.  Other  factories  are  paying  a  stated  price  for  all  milk  test- 
ing say  4  per  cent,  fat  and  over,  and  make  corresponding  reductions 
for  milk  containing  less  than  4  per  cent.  Still  others  pay  a  premium 
for  milk  testing  over  4  per  cent.  fat.  A  few  concerns  only  are  buy- 
ing their  milk  on  the  butter  fat  basis. 

As  far  as  the  condensery  is  concerned  it  would  be  entirely 
feasible  to  pay  for  all  milk  strictly  on  the  butter  fat  basis.  Milk  rich 
in  fat,  and  therefore  rich  in  solids,  yields  more  condensed  milk  than 
milk  poor  in  fat.  To  pay  by  the  hundred  weight,  regardless  of  qual- 
ity is  a  practice  which  discriminates  in  favor  of  breeds  of  low-test- 
ing milk  and  against  breeds  of  high-testing  milk.  For  the  sake  of 
justice  to  the  milk  producer,  it  is  to  be  hoped  that  the  milk  con- 
densing companies  may  soon  break  away  from  old  traditions  and 
antiquated  practices,  and  adopt  the  only  fair  and  up-to-date  method 
of  buying  milk  on  the  butter  fat  basis. 

Quality.— The  quality  of  the  fresh  milk  is  the  first  and  most 
important  factor  to  be  considered.     The  milk  condensing  factory, 


28  Condensed  Milk  and  Milk  Powder 

ignoring  this  fact  and  accepting  milk  from  unsanitary  dairies  and 
careless  dairymen,  is  bound  to  pay  the  penalty  for  such  neglect 
sooner  or  later. 

Polluted  milk  and  milk  that  has  not  been  cooled  promptly  and 
to  a  reasonably  low  temperature  on  the  farm,  may  pass  through  the 
process  successfully,  if  it  is  not  too  sour.  The  condensed  milk  made 
from  it,  though,  is  inferior  in  Havor  and  keeping  quality,  and  usually 
shows  signs  of  deterioration  and  decay  before  it  reaches  the  con- 
sumer. The  risk  of  handling  such  milk  is  very  great ;  it  often  re- 
sults in  total  loss  to  the  manufacturer.  The  trouble  may  and  often 
does  begin  before  the  process  is  completed.  Unclean,  abnormal,  or 
partly  fermented  milk,  when  subjected  to  the  process,  is  prone  to 
curdle  and  whey  of¥ ;  the  condensed  milk  becomes  lumpy  and  shows 
other  defects.  This  is  especially  true  where  superheating  is  prac- 
ticed and  where  evaporated  milk  is  made. 

Milk  that  has  received  the  best  of  care  on  the  farm  may  be 
detrimental  to  the  interests  of  the  condensery,  if  it  comes  from 
cows  less  than  thirty  days  before  their  parturition,  or  from  fresh 
cows  within  the  first  seven  days  after  calving.  Such  milk  is  often 
abnormal  in  its  chemical  properties,  and,  when  subjected  to  high 
temperatures,  undergoes  changes  that  make  its  manufacture  into  a 
marketable  condensed  milk  difficult. 

Control  of  Quality. — Every  well  nianaged  milk  condensing  fac- 
tory plays  the  part  of  an  educator  in  the  production  of  sanitary 
milk.  The  condensery  usually  issues  a  set  of  rules,  setting  forth 
specifically  the  conditions  under  which  the  milk  coming  to  the  fac- 
tory shall,  or  shall  not  be  produced.  Copies  of  these  rules,  which  are 
generally  a  part  of  the  contract,  are  placed  in  the  hands  of  all  pa- 
trons. The  condensery  employs  one  or  more  dairy  inspectors  whose 
business  it  is  to  .see  that  the  rules  are  rigidly  enforced.  These  rules 
cover,  in  general,  the  following  principal  points : 

1.  Cows. — The  milk  must  come  from  healthy  cows.  Milk  from 
cows  that  afe  diseased,  or  that  have  a  diseased  udder,  or  that  are 
otherwise  in  poor  physical  condition,  will  be  rejected. 

2.  Feed  and  Water. — Do  not  feed  weeds,  roots,  or  other  feed 
stufifs  possessing  strong  and  obnoxious  odors,  such  as  onions,  gar- 
lic, turnips,  cabbage,  wet  distillery  slops,  decayed,  musty  or  sour 


Condensed  Mii.k  and  Mii^k  Powder  29 

silage,  or  other  fermented  feed.  (Some  condenseries  prohibit  the 
use  of  all  silage.  This  restriction  betrays  prejudice  and  ignorance 
on  the  part  of  the  management  concerning  the  great  value  and  aD- 
solute  harmlessness  of  good  silage  as  a  dairy  feed.  It  is  an  injury 
to  the  dairy  interests  of  the  country.  Corn  silage  or  other  silage,  in 
good  condition,  and  fed  in  reasonable  quantities,  does  in  no  way  in- 
jure the  milk  for  condensing  purposes).  The  cows  must  be  sup- 
plied with  clean,  fresh  water. 

3.  Lactation  Period. — Reject  all  milk  from  cows  less  than 
thirty  days  before,  and  of  the  first  seven  days  after  calving. 

4.  Milkers  and  Milking. — Milk  with  clean,  dry  hands  into 
clean  utensils  and  remove  the  milk  to  the  milk  room  immediately 
after  drawn. 

5.  Straining. — Strain  the  milk  in  the  milk  room  through  a  fine 
wire  m.esh  strainer  (80  to  100  meshes  to  the  inch).  Do  not  use 
cloth  strainers. 

6.  Cooling.— Cool  the  milk  to  60  degrees  F.  or  below  and  keep 
it  at  that  temperature  until  it  reaches  the  factory.  Do  not  mix  the 
warm  morning's  milk  with  the  cold  night's  milk ;  cool  the  morning's 
milk  before  mixing,  or  send  it  to  the  factory  in  separate  cans. 

7.  Care  of  Utensils. — Rinse  with  cold  water,  wash  with  warm 
water  and  washing  powder,  and  rinse  with  boiling  water  all  milk 
utensils  thoroughly  after  use ;  keep  them  in  a  clean  place  between 
milkings.  Do  not  store  the  milk  on  the  farm  in  cans  that  have  not 
been  washed  by  the  factory. 

8.  Stables. — Whitewash  the  stable  twice  every  year  and  re- 
move manure  daily.  (Some  condenseries  furnish  spray  pumps  for 
applying  whitewash). 

Inspection  of  Milk  at  the  Condensery.— At  the  condensery 

the  milk  is  subjected  to  rigid  inspection  by  a  man  who  is,  or  should 
be,  an  expert  on  milk  inspection ;  every  can  is  examined.  Warm  milk 
and  milk  that  is  tainted,  or  smells  slightly  sour  should  be  rejected. 
Inspection  of  Milk  by  Sense  of  Smell  and  Taste. — In  most 
cases  the  milk  is  inspected  with  reference  to  odor.  The  inspector 
quickly  raises  the  cover  of  each  can  to  his  nostrils.  The  odor  in 
the  cover  is  typical  of  that  in  the  can.  If  it  is  "off,"  the  can  is  re- 
jected.    An  experienced  man  on  the  platform  can,  by  the  use  of 


30  CoNDENSiiD  Milk  and  Milk  Powder 

this  method,  tell  with  much  accuracy,  whether  the  milk  should  pass 
or  not. 

Inspection  of  Milk  According  to  its  Tempe;rature. — The 
temperature  is  also  noted.  This  need  not  be  done  with  the  ther- 
mometer in  each  case.  By  placing  his  hand  on  the  body  of  the  can, 
or  by  noting  the  warmth  of  the  air  and  odor  in  the  cover  immediate- 
ly after  removing  it,  or  by  the  presence  or  absence  of  small  par- 
ticles of  butter  floating  on  the  surface  of  the  milk,  the  inspector 
can  readily  tell  if  the  milk  has  or  has  not  been  properly  cooled.  A 
correct  thermometer  should  always  be  on  the  platform  for  guidance. 

Inspection  of  Milk  by  the  Use  of  Acid  Tests. — Since  the 
degree  of  acidity,  or  the  sweetness  of  the  milk,  is  one  of  the  chief 
factors  that  determines  its  fitness  for  condensing  purposes,  tests 
that  rapidly  and  accurately  determine  the  per  cent,  of  lactic  acid  in 
the  fresh  milk,  are  of  great  service. 

Some  concerns  have  adopted  a  definite  standard  of  milk,  re- 
jecting all  milk  containing  more  than  the  maximum  per  cent,  of 
acid  of  their  standard,  and  they  test  every  can  of  milk  received  with 
an  acid  test.  This  method  insures  sweet  milk  in  the  factory,  pro- 
vided that  the  alkaline  solutions  used  are  correct.  This  work  in- 
volves considerable  expense,  however,  and  unless  the  solution  is 
carefully  prepared  and  made  up  fresh  often,  its  use  may  yield  mis- 
leading results.  Again,  when  the  acid  test  is  performed  on  the  milk 
of  each  can,  the  acceptance  or  rejection  of  the  milk  depends  alto- 
gether on  the  per  cent,  of  acid  it  contains.  Although  milk  may  be 
otherwise  unfit  for  use,  it  will  pass,  as  long  as  it  is  low  in  acidity. 
Experience  has  shown  that,  while  it  is  necessary  for  the  condensery 
to  decide  on  a  maximum  acidity  of  milk  above  which  all  milk  be  re- 
jected, the  nose  and  the  palate  of  the  experienced  inspector  are 
better  cwterions  than  the  acid  tests  alone,  as  to  the  fitness  of  milk  for 
condensing.  Acid  tests  are  valuable  in  the  case  of  uncertainty  and 
suspicion  as  to  the  quality  of  any  given  can  of  milk.  All  milk  con- 
taining .2  per  cent,  lactic  acid  or  more  is  dangerous  for  condensing 
purposes  and  should  be  rejected. 

Acid  Test  for  Daily  Use,  Where  Each  Can  of  Milk  is  Tested.— 
Stock  Solution. — \\'eigh  out  two  hundred  grams  of  sodium  hydrate 
C.  P.  and  add  distilled  water  to  make  up  one  liter.  Keep  tightly 
stoppered. 


Condensed  Milk  and  Milk  Powder  31 

Solution  for  Daily  Use. — Mix  4  c.c.  of  stock  solution  with  991 
c.c.  of  distilled  water,  and  add  5  c.c.  of  phenolphthalein  indicator. 
The  indicator  is  prepared  as  follows :  dissolve  one  gram  of  dry 
phenolphthalein  in  100  c.c.  of  50  per  cent,  alcohol.  Each  cubic 
centimeter  of  the  prepared  alkaline  solution  neutralizes  .01  per  cent, 
lactic  acid,  20  c.c.  of  the  prepared  solution,  therefore,  neutralize  .2 
per  cent,  lactic  acid,  when  a  17.6  c.c.  pipette  is  used  for  measuring 
out  the  milk. 

Making  the  Test. — With  the  Babcock  pipette,  measure  17.6  c.c. 
into  a  white  cup.  With  a  small  dipper,  holding  exactly  20  c.c,  pour 
20  c.c.  of  the  prepared  solution  into  the  cup;  stir  or  shake.  If  the 
mixture  remains  faintly  pink,  it  contains  less  than  .2  per  cent,  acid 
and  will  pass ;  if  it  turns  wihite,  it  contains  more  than  .2  per  cent, 
acid  and  should  be  rejected. 

The  stock  solution  should  be  standardized  by  a  chemist.  The 
prepared  solution,  should  be  made  up  daily.  Both  solutions  should 
be  kept  in  glass  bottles,  tightly  corked.  The  bottle  containing  the 
stock  solution  should  be  glass-stoppered. 

Acid  Test  for  Use  on  Suspicious  Cans  Only. — The  Farrington 
Alkaline  Tablet  Test.  Use  an  eight  ounce,  wide-mouth  bottle,  place 
in  it  sixteen  Farrington  alkaline  tablets,  add  eight  ounces  of  distilled 
water  or  rain  water,  or  any  pure  water  relatively  free  from  car- 
bonates. Stopper  tightly  and  let  stand  for  six  hours,  or  until  the 
tablets  are  completely  dissolved.  This  solution  neutralizes  .2  per 
cent,  of  lactic  acid  in  equal  parts  of  milk. 

Making  the  Test. — Use  small  dip])ers  of  the  same  size  for  milk 
and  for  test  solution.  Pour  into  a  white  cup  one  dipperful  of  milk 
and  one  dipperful  of  solution.  If  the  mixture  turns  white,  it  con- 
tains more  than  .2  per  cent,  lactic  acid  and  should  be  rejected.  If 
it  remains  pink,  the  milk  contains  less  than  .2  per  cent  acid. 

The  Boiling  Test.  Inspection  by  Heating. — The  heating 
to  the  boiling  point  of  samples  of  suspicious  milk  furnishes  a  most 
reliable  means  to  determine  the  fitness  of  such  milk  for  condensing. 
In  many  instances  milk  may  satisfactorily  pass  the  other  tests  and 
yet  it  may  not  be  in  condition  to  stand  the  heat  to  which  it  will  be 
subjected  in  the  process.  If  it  curdles,  when  boiled,  it  is  obviously 
unfit  for  use.  This  test  shows  more  than  the  acid  test  above.  By 
its  use  the  operator  is  able  to  detect  milk  otherwise  abnormal,  such 


32 


Condensed  Milk  and  Milk  Powder 


as  milk  containing  colostrum,  etc.,  or  the  proteids  of  which  are  un- 
stable for  other  reasons. 

Making  the  Test. — The  boiling  test  is  simple  and  can  be  ma- 
nipulated rapidly.  A  sample  of  the  questionable  milk  is  taken  into 
a  small  dipper.  The  dipper  is  held  up  against  a  steam  jet  turned 
down  into  the  milk.  Direct  steam  is  turned  into  the  milk  until  it 
comes  to  a  boil.  If  flakes  or  specks  of  curd  cling  to  the  sides  of  the 
dipper,  the  milk  is  unfit  for  use. 

An  alcohol  lamp  or  gas  burner  on  the 
platform  may  be  used  for  heating  the  sam- 
ple. In  this  case  a  few  cubic  centimeters  of 
the  milk  are  discharged  with  an  ordinary 
pipette  into  an  ordinary  test  tube,  such  as 
are  in  common  use  in  the  chemical  labora- 
tory and  can  be  obtained  from  the  drug 
store.  The  tube  is  held  over  the  flame  and 
the  milk  comes  to  a  boil  in  less  than  a  min- 
ute. If  the  milk  is  in  good  condition  the 
sides  of  the  glass  tube  remain  perfectly  clear. 
If  it  curdles  upon  heating,  the  sides  of  the 
tube  show  fine  specks  of  curd.  The  appear- 
ance of  these  specks  condemns  the  milk. 

The  Sediment  Test. — This  test  shows 
the  relative  amount  of  dirt  present  in  milk. 
One  half  pint  of  milk  is  passed  through  a 
small  circle  of  absorbent  cotton  and  the 
amount  of  mechanical  impurities  present  in  the  milk  is  indicated  by 
the  color  of  the  cotton  after  filtration.  In  order  to  hasten  the 
filtration,  the  milk  is  forced  through  the  filter  under  slight  pressure. 
This  is  accomplished  by  a  rubber  bulb  attachment  to  the  ai)paratus, 
as  shown  in  the  accompanying  figure. 

If  the  cotton  retains  a  white  or  creamy  color,  the  milk  is  rela- 
tively free  from  filth.  Milk  produced  under  unsanitary  conditions 
stains  the  cotton  brown  or  black. 

These  cotton  filters  may  be  pasted  on  a  sheet  of  paper  similar 
to  a  milk  sheet,  arranged  so  that  the  circles  are  placed  opposite  the 
respective  patron's  name  or  number.  When  shown  to  the  patrons 
who  come  to  the  factory,  they  furnish  a  most  effective  object  lesson 
to  them.     When  the  milk  reaches  the  factory  on  route  wagons^ 


Fig.    5. 
The  sediment  tester 


Condensed  Milk  and  Milk  Powder 


33 


Fig.  (i.     Cotton  Filters 


Dirty  milk 


by  rail,  cards  similar  to  Figure  7  may  be  mailed  to  the  patrons. 
The  evidence  is  so  conclusive  that  even  the  most  obstinate  patron 
can  not  help  admitting  his  guilt  and  can  usually  be  induced  to  "clean 
up." 


MILK  CONDENSING   COMPANY 

SEDIMENT   CARD 

Namt 

THIS    IS    THE    AMOUNT    OF    DIRT    IN 
ONE    PINT    OF    YOUR    MILK 

AnnRF=;c: 

Datf 
No 

Fermentation  Tests. — These  tests  are  of  great  value  in  the 
rapid  determination  of  the  kind  of  bacteria  with  which  the  milk 
from  individual  patrons  is  contaminated.  Glass  tubes  are  filled 
one  half  full  of  milk  from  each  patron.  These  tubes  are  set  in  a 
constant  water  bath  at  100  degrees  F.  and  the  changes  which  milk 
undergoes  are  noted  after  six,  twelve  and  twenty-four  hours. 

A  solid  curd  with  a  clear  whey  indicates  that  lactic  acid  bac- 
teria are  the  chief  organisms  and  that  the  milk  has  been  produced 
under  cleanly  conditions.    These  organisms  are  killed  when  the  milk 


34  Condensed  Miek  and  Milk  Powder 

is  heated  in  the  hot  wells.     Such  milk  therefore  is  safe,  unless  it 
contains  excessive  acid,  as  shown  by  the  acid  test. 

A  curd  with  gas  holes,  or  that  which  is  torn  to  pieces  in  the 
tubes,  shows  the  presence  of  gas-producing  germs.  These  come  largely 
from  manure  and  other  filth.  Among  these  are  Bacillus  coli  com- 
munis, the  natural  inhabitant  of  the  colon  of  the  animal,  and  butyric 
acid  organisms  which  are  spore  bearers.  The  latter  especially  may 
give  rise  to  serious  milk  defects,  causing  "swell  heads."  Patrons 
sending  such  milk  should  be  looked  after  at  once. 

If  the  curd  dissolves  or  no  curd  is  formed  and  the  milk 
changes  into  a  transparent  liquid,  it  usually  is  contaminated  by 
germs  from  the  dust  of  hay  and  bedding,  or  polluted  water.  To 
this  class  of  organisms  belong  Bacillus  subtilis,  Bacillus  fluorescens 
liquifaciens,  Plectridiumi  foetidium,  Bacillus  putrificus,  etc.  Some 
of  these  are  violent  gas  producers  and  most  of  them  are  spore  bear- 
ers. They  are  the  cause  of  some  of  the  most  disastrous  milk  de- 
fects. Dairies  from  which  such  milk  comes  should  be  vigorously 
inspected  and  all  milk  from  them  should  be  rejected,  until  the  pa- 
trons have  learned  how  to  furnish  sanitary  milk. 

Milk  that  remains  unchanged  for  twenty-four  hours  when  sub- 
jected to  the  fermentation  test,  suggests  that  it  contains  some  pre- 
servative. It  is  possible,  however,  for  milk  produced  under  ideally 
sanitary  conditions  to  remain  normal  and  unchanged  even  at  these 
high  temperatures  for  several  days.  Where  milk  comes  to  the  fac- 
tory in  bulk  as  is  the  case  in  the  condensery,  samples  showing  ab- 
normal keeping  quality  should  be  regarded  with  suspicion,  and  the 
respective  dairies  should  receive  immediate  and  thorough  inspec- 
tion. 

Tests  for  Butterfat  and  Specific  Gravity. — In  the  fac- 
tories where  the  milk  is  not  paid  for  on  the  butter 
fat  basis,  composite  samples  should  be  taken  daily,  to  be  tested  for 
fat  and  specific  gravity,  at  regular  intervals  of  from  two  to  four 
weeks,  in  order  to  detect  possible  adulterations  by  skimming  or  by  the 
addition  of  water.  For  specific  directions  for  the  Babcock  test,  the 
use  of  the  lactometer  and  tests  for  preservatives  see  Chapter 
XXIX  "Chemical  Tests  and  Analyses  of  Milk  and  Milk  Products" 
and  Chapter  XXX  "Detection  of  Adulterants  and  Preservatives, 
Etc." 


Condensed  Milk  and  Milk  Powder  35 

FACTORY  SANITATION 

In  the  previous  paragraphs,  special  emphasis  was  placed  on  the 
great  importance  of  a  good  quality  of  fresh  milk.  It  is  equally  es- 
sential that  the  factory  be  kept  in  exemplary  condition  as  to  clean- 
liness and  sanitation.  This  is  necessary  because  of  its  effect  on  the 
patrons,  on  the  wholesomeness  and  on  the  marketable  property  of 
the  finished  product. 

Effect  on  Patrons.— It  does  not  take  the  watchful  eye  of  the 
intelligent  patron,  who  daily  comes  to  the  factory,  very  long  to  learn, 
whether  the  manufacturer  gives  his  milk  as  good  care  as  he  gave 
it  on  the  farm.  A  good  example  set  by  the  factory  will  mean  much 
toward  instilling  the  patron  with  ambition  to  do  likewise  on  the 
farm.  Shiftlessness  is  a  contagious  disease,  to  which  the  average 
farmer  is  very  susceptible.  It  is,  therefore,  inconsistent  for  the 
factory  to  issue  and  enforce  rules  of  sanitation  for  the  dairy  farmer 
when,  within  its  own  walls,  all  principles  of  sanitation  are  violated. 

Effect  on  Wholesomeness  of  the  Product.— Uncleanliness  and 
filth  interfere  with  the  wholesomeness  of  the  product.  Con- 
densed milk  made  in  a  factory  ignoring  sanitation,  may  contain  cer- 
tain products  of  decay  which  are  poisonous  to  the  human  system. 
Again,  it  may  contain  germs  of  infectious  diseases  and  thus  become 
the  cause  of  widespread  epidemics  of  these  diseases  and  possibly 
claim  many  victims.  As  a  matter  of  common  decency  and  of  duty 
to  the  commonwealth,  the  condensery  should  pay  close  attention  to 
cleanliness  in  all  operations. 

Effect  on  the  Marketable  Property  of  the  Product.— Again, 

uncleanliness  in  the  factory  is  bound  to  bring  financially  disastrous 
results.  The  seriousness  of  the  disaster  is  greatly  augmented  by  the 
fact  that  the  consequences  of  neglect  are  usually  not  apparent  until 
after  the  goods  have  reached  the  market.  The  pollution  of  con- 
densed milk  with  impurities  and  filth  in  the  factory,  shortens  the 
life  of  the  product.  Such  condensed  milk  is  of  very  poor  keeping 
quality.  It  may  reach  the  market  and  the  consumer  in  condition 
that  causes  it  to  be  rejected,  resulting  in  a  complete  loss  to  the  man- 
ufacturer. The  manufacturer  allowing  such  conditions  to  exist, 
is  usually  the  last  man  to  realize  and  admit  that  he  is  at  fault,  which' 


36  Condensed  Milk  and  Milk  Powder 

renders  attempts  to  locate  and  stop  such  defects  exceedingly  diffi- 
cult.    Furthermore,  instead  of  helping  to  build  up  the  trade  and  to 

advertise  the  brand,  he  demoralizes  it. 

How  to  Keep  Factory  in  Sanitary  Condition. — Cleanliness  in 
the  factory  is  absolutely  essential.  The  milk  vats  should  be  rinsed 
with  plenty  of  water  and  scrubbed  and  steamed  thoroughly,  as  soon 
as  possible  after  use.  The  copper  kettles  and  vacuum  pans  should 
be  rinsed,  then  scoured  with  sandpaper  or  emery  cloth,  then  rinsed 
and  steamed  thoroughly.  The  milk  pipes  should  be  scoured  by  run- 
ning flue  brushes  through,  flushing  them  with  clean  water  and 
steaming  them  until  tliey  are  scalding  hot.  In  the  case  of  milk 
pipes  of  excessive  length,  they  should  be  well  flushed  with  hot  alka- 
line water.  Milk  pumps  should  be  taken  apart  every  day  and  freed 
thoroughly  from  all  remnants  of  milk.  The  water  in  the  cooling 
tanks,  should  be  changed  as  often  as  is  necessary  to  insure  clean 
water  in  them  at  all  times.  The  homogenizer  should  receive  special 
attention,  all  its  valves  should  be  thoroughly  cleaned  and  steamed 
daily.  The  cooling  coils  should  be  scalded  before  use.  The  filling 
machines  for  evaporated  milk  should  be  freed  from  all  milk,  rinsed 
and  steamed  thoroughly  and  no  remnants  of  milk  should  be  allowed 
to  stick  to  the  valves.  The  filling  machines  for  sweetened  con- 
densed milk  should  be  emptied  and  compijetely  washed,  at  least  once 
per  week,  and  protected  from  dust  and  filth  by  covering  them  when 
not  in  use.  The  tin  cans  should  be  stored  in  a  clean  room  and  every 
precaution  should  be  taken  to  guard  against  their  defilement  from 
dirt,  dust,  insects  and  mice.  Where  possible  they  should  be  sterilized 
before  use. 

All  vats,  kettles,  milk  conveyors,  vacuum  pans,  milk  pumps,  and 
all  machinery  coming  in  contact  with  milk,  should  be  flusbed  and 
steamed  again  in  the  morning,  as  soon  as  the  condensery  opens.  The 
sugar  chute  should  be  kept  clean,  care  being  taken  that  no  damp  or 
wet  sugar  remains  in  it.  Special  attention  should  be  given  to  the 
washing  of  the  farmers'  cans.  After  washing  with  brush  and  hot 
water  containing  some  good  washing  powder,  they  should  be  thor- 
oughly rinsed,  then  steamed  until  they  are  hot.  If  possible  they 
should  be  dried  by  an  air  blast. 


Condensed  Milk  and  Milk  Powder  37 


PART  II 

MANUFACTURE  OF  SWEETENED 
CONDENSED  MILK 

CHAPTER  IV 

DEFINITION 

Sweetened  condensed  milk  is  cow's  milk,  condensed  at  the  ratio 
of  2I/2  to  2%  parts  of  fresh  milk  to  i  part  condensed  milk.  It  con- 
tains considerable  quantities  of  sucrose,  usually  about  40  per  cent., 
to  preserve  it.  It  is  of  semi-fluid  consistency  and  reaches  the  mar- 
ket in  hermetically  sealed  tin  cans,  varying  in  size  from  eight  ounces 
to  one  gallon,  and  in  barrels  similar  to  glucose  barrels,  holding  from 
three  hundred  to  seven  hundred  pounds  of  condensed  milk.  When 
made  properly,  sweetened  condensed  milk  will  keep  for  many 
months,  but  is  best  when  fresh. 

HEATING 

Purpose. — The  first  step  in  the  process  is  to  heat  the  milk  to 
near  the  boiling  point.  There  are  three  chief  reasons  for  which  the 
milk  is  heated,  namely  to  destroy  most  of  the  bacteria,  yeast,  molds 
and  other  organized  and  unorganized  ferments,  to  facilitate  the  so- 
lution of  the  sucrose,  and  to  prevent  the  milk  from  burning  on  to 
the  heating  surface  in  the  vacuum  pan. 

Destruction  of  Ferments.— When  the  fresh  milk  arrives  at 
the  factory  it  contains  micro-organisms  in  varying  numbers  and  of 
different  species.  In  some  cases  disease-producing  bacteria  may  be 
present,  rendering  the  milk  dangerous  to  the  health  and  life  of  the 
consumer,  were  it  not  heated  to  temperatures  high  enough  to  de- 
stroy these  germs.  Again,  milk  may  contain  bacteria,  yeast,  molds 
and  enzymes  that  cause  it  to  undergo  undesirable  fermentations 
which,  if  allowed  to  pass  into  the  condensed  milk,  may  tend  to 
shorten  the  life  and  impair  the  wholesomeness  and  marketable  prop- 
erties of  the  latter. 


38  CoNDivNSED  Milk  and  Milk  Powder 

Solution  of  Sucrose. — It  is  very  essential  that  all  the  cane  su- 
gar wliich  is  added  to  the  milk,  ibe  completely  dissolved,  in  order  to 
lessen  the  tendency  of  the  sugar  to  crystallize  in  the  finished  prod- 
uct. Undissolved  sugar  crystals  in  condensed  milk,  act  in  a  physical 
way  much  as  bacteria  in  fluid  milk  do  in  a  bacteriological  way.  They 
multiply  rapidly,  and  such  condensed  milk  usually  precipitates  its 
sugar  before  the  product  reaches  the  market.  The  presence  of  ex- 
cessive sugar  crystals  makes  the  product  gritty  and  causes  the  for- 
mation of  a  sediment  in  the  bottom  of  the  cans;  this  is  objectionable 
to  the  consumer.  When  the  milk  is  heated  to  the  proper  tempera- 
ture before  condensing,  the  solution  of  the  cane  sugar  is  facilitated 
and  the  tendency  toward  grittiness  is  minimized. 

Prevention  oe  Burning  Milk  on  Heating  Surface. — If  cold 
milk  comes  in  contact  with  a  steam-heated  surface  and  is  not  agi- 
tated vigorously,  it  bakes  or  burns  onto  this  heating  surface.  The 
milk  in  the  vacuum  pan  is  heated  or  kept  hot  by  means  of  the  steam 
jacket  and  coils.  These  radiators  are  charged  with  steam  under 
pressure  and  consequently  give.ofif  a  high  degree  of  heat.  If  cold 
milk  is  drawn  into  the  vacuum  pan,  the  milk  remains  calm  for  a 
considerable  length  of  time.  During  this  time  it  is  bound  to  bake 
or  burn  on  the  heating  surface,  giving  the  product  a  burnt  flavor, 
causing  it  to  contain  brown  specks  and  retarding  the  process  of 
evaporation.  If  the  milk  is  hot  when  it  enters  the  pan,  the  reduced 
pressure  in  the  pan  causes  it  to  boil  violently  at  once,  avoiding  all 
danger  of  sticking  to  and  burning  on  the  heating  surface, 

Temperature. — In  most  factories  the  milk  is  heated  to  from 
180  degrees  F.  to  200  degrees  F.  This  temperature  is  sufficient  to 
accomplish  the  three  purposes.  Heating  the  milk  to  the  boiling  point 
tends  to  give  it  a  rather  pronounced  cooked  flavor,  which  is  objec- 
tionable. However,  in  the  case  of  danger  of  contamination  of  the 
milk  with  resistant  types  of  undesirable  bacteria,  it  may  become  nec- 
essary to  practice  boiling  the  milk. 

Manner  of  Heating. — Thorough,  efficient  and  rapid  heating 
of  large  volumes  of  milk  to  temperatures  near  the  boiling  point  is  a 
problem  that  requires  careful  consideration.  The  tendency  of  the 
milk  to  stick  to  the  heating  surface  is  a  permanent  obstacle  and  ef- 
forts to  overcome  this  frequently  result  in  sacrificing  thoroughness 
of  heating. 


Condensed  Milk  and  Milk  Powder 


39 


A  variety  of  methods  and  numerous  different  types  of  ma- 
chines are  used  for  this  purpose  in  the  dift'erent  milk  condensing 
factories.  Some  use  large  copper  kettles  in  which  the  milk  is  heat- 
ed by  turning  steam  direct  into  the  milk.  Others  use  jacketed  cop- 
per kettles  equipped  with  a  revolving  agitator.  The  milk  is  heated 
by  turning  steam  under  pressure  in- 
to the  jacket  and  the  burning  of  the 
milk  is  prevented  by  keeping  the  milk 
in  constant  motion.  Still  others  are 
heating  the  milk  by  means  of  large 
continuous  pasteurizers  of  the  Miller 
type,  in  which  case  hot  water  serves 
as  the  heating  medium.  The  milk 
passes  in  a  thin  layer  between  two 
water-heated  surfaces,  one  of  which  is 
revolving.  In  some  factories  the  milk 
is  forced  through  a  series  of  pipes 
inclosed  in  a  hot  water  or  steam 
jacket. 

Finally,  in  some  condenseries 
a  combination  of  the  continuous 
pasteurizer  and  the  jacketed  kettle  is  used.  The  milk  is  heated  to 
nearly  the  desired  temperature  in  the  pasteurizer.  From  there  it 
flows  into  the  jacketed  kettle.  This  kettle  is  so  constructed  that 
when  steam  is  turned  into  the  jacket,  the  milk  rises  and  it  flows  over 
and  off  into  the  sugar  well.  This  insures  efficient  heating  and,  at 
the  same  time,  if  operated  properly,  it  prevents  the  baking  of  the 
milk  on  the  heating  surface.  The  disadvantage  of  this  double  sys- 
tem of  heating  is  that  the  overflowing  kettle  has  to  be  watched  very 
closely. 


Fig.  8.     The  hot  well  or  forewarmer 

Courtesy   of  Arthur  Harris  &   Co. 


Advantages  and  Disadvantages  of  Different  Methods  of  Heat- 
ing.— In  most  factories,  in  this  country,  the  first  named  method  is 
used.  Steam  is  turned  direct  into  the  milk  until  it  boils  up.  This  is 
the  oldest  and  most  primitive  method.  While  very  simple  in  opera- 
tion, this  method  has  serious  objections.  At  best,  much  of  the 
steam  used  condenses  in  the  milk,  increasing  the  amount  of  water 
that  has  to  be  evaporated.  It,  therefore,  prolongs  the  process  of 
condensing  and  increases  the  cost  of  manufacture.     This  is  espe- 


40  Condensed  Milk  and  Milk  Powder 

cially  true  where  the  boilers  are  located  at  some  distance  from  the 
hot  wells  and  the  steam  pipes  are  not  well  insulated,  causing  the 
steam  to  be  "wet."'  It  is  estimated  that  the  amount  of  extraneous 
water  thus  added  to  the  milk,  increases  the  bulk  of  the  milk  by  one- 
sixth  of  its  original  volume.  The  steam  is  often  associated  with 
impurities,  such  as  cylinder  oil  from  the  engine,  boiler  compounds 
used  in  the  boilers,  scales  from  the  inside  of  the  pipes,  etc.  These 
various  impurities  cannot  possibly  improve,  but  may  seriously  injure 
the  quality  of  the  milk.  It  is  quite  probable,  also,  that  the  direct 
contact  of  live  steam  with  milk,  has  no  beneficial  eflfect  on  its  ingred- 
ients. It  is  generally  conceded  by  those  who  have  given  this  matter 
careful  thought,  that  the  turning  of  steam  direct  into  the  milk 
shortens  the  life  of  the  product  and  causes  it  to  develop  a  stale 
flavor,  which  may  degenerate  into  an  oily  flavor.  The  same  defect  is 
noted  also  when  cream  is  heated  by  turning  steam  into  it.  The  pro- 
longed exposure  of  the  milk  to  the  condensing  process,  as  the  result 
of  the  addition  to  the  milk  of  considerable  quantities  of  condensed 
steam,  further  may  be  injurious  to  the  milk. 

Any  method  of  heating  that  does  not  require  direct  contact  of 
the  steam  with  the  milk  is  preferable,  provided  that  it  makes  possible 
thorough  heating  to  the  Required  temperature  without  burning  the 
milk.  Practically  all  of  the  other  methods  above  referred  to  accom- 
plish this. 

ADDITION  OF  SUGAR 

Considerable  quantities  of  sucrose  are  added  to  the  condensed 
milk  for  the  purpose  of  preserving  it. 

Kinds  of  Sugar. — In  order  to  convey  to  the  milk  preservative 
properties,  that  kind  of  sugar  must  be  used,  which  does  not  readily 
undergo  fermentation  and  which  has  the  power  of  inhibiting  bac- 
terial activity  when  dissolved  in  a  concentrated  solution.  Glucose 
could  be  purchased  at  a  very  low  cost,  but  it  is  not  suitable  for  this 
purpose,  since  it  is,  in  itself,  very  unstable  and  fermentable.  It  has 
no  preservative  qualities,  even  in  concentrated  solutions.  Sucrose, 
saccharose,  or  cane  sugar,  CioH^oOn,  properly  refined,  ferments 
with  difificulty  in  concentrated  solutions,  and  has  the  power  of  re- 
tarding the  growth  of  bacteria  and  other  ferments  ordinarily  present 
in  sweetened  condensed  milk.  It  is,  therefore,  very  satisfactory  and 
useful  in  this  connection. 


Condensed  Miek  and  Milk  Powder  41 

Beet  sugar,  which  is  chemically  identical  with  cane  sugar,  is 
used  in  European  countries  very  largely  in  the  place  of  cane  sugar. 
On  the  continent  the  beet  sugar  industry  is  an  important  factor. 
With  the  climate  adapted  to  the  growing  of  sugar  beets  and  the 
labor  relatively  cheap,  beet  sugar  can  be  secured  by  the  European 
conden series  at  lower  cost  than  cane  sugar.  In  America  where  the 
annual  sugar  cane  crop  is  large  and  where  the  high  cost  of  labor 
renders  the  expense  of  growing  sugar  beets  relatively  high,  there 
is  practically  no  difference  between  the  price  of  cane  sugar  and  beet 
sugar.  When  American  beet  sugar  was  used  in  the  condenseries 
during  the  infancy  of  the  beet  sugar  industry,  this  sugar  was  found 
undesirable,  often  giving  rise  to  fermented  condensed  milk.  It  was 
then  supposed  by  the  condensed  milk  men,  that  beet  sugar  contained 
very  resistant  spore-bearing  bacteria,  whidi  followed  the  beets  from 
the  soil  into  the  refined  sugar..  This  conclusion  is  highly  improb- 
able, as  the  temperatures  and  chemicals  employed  in  the  process  of 
beet  sugar  making,  are  prohibitive  of  the  passage  of  living  bacteria 
from  the  soil  to  the  finished  sugar.  It  is  possible,  however,  that 
the  standard  of  refinement  of  American  beet  sugar,  during  the  ear- 
lier days  of  its  manufacture,  was  low  and  that  some  of  the  beet 
sugar  on  the  market  may  have  contained  small  amounts  of  acid, 
invert  sugar  and  other  impurities,  ingredients  of  such  a  nature  as  to 
render  the  sugar  prone  to  give  rise  to  fermentation  and,  therefore, 

condemn  its  use  in  the  milk  condenserv- 
♦I 
W'hile  the  beet  sugar  on  the  market  to-day  appears  to  have 

reached  a  very  high  state  of  refinement  and  is,  according  to  the  best 

authorities,  equal  in  purity  to  cane  sugar,  it  is  still  shunned  by  the 

American  condenseries,  which  insist  that  nothing  but  cane  sugar  will 

do.     However,  the  total  beet  sugar  production  in  the  United  States 

has  more  than  trebled  within  the  last  ten  years.    In  1901  it  amounted 

to  one  hundred  eighty-four  thousand  tons  and  in  191 1  it  was  six 

hundred   six  thousand  and   thifty-three  tons.     Again,  whenever   a 

shortage  occurs  of  the  sugar  cane  crops  in  the  West  Indies,  raw 

European  beet  sugar  is  imported  into  the  United  States  and  it  aW 

emerges  from  our  seaboard  refineries  as  "pure  cane  sugar."     It  is 

not  improbable,  therefore,  that  the  sugar  supply  of  many  American 

condenseries  today  consists  at  times  largely  of  beet  sugar,  though  it 

is  purchased  under  the  name  of  cane  sugar. 


42  Condensed  Milk  and  Milk  Powder 

There  is  no  good  reason  why  the  best  refined  beet  sugar,  manu- 
factured today  in  this  country  and  elsewhere,  should  not  give  full}- 
as  good  results  for  condensing  purposes,  as  the  same  quality  of  cane 
sugar.  Tests  made  at  the  California  Agricultural  Experiment  Sta- 
tion^ led  to  the  conclusion  that  the  two  kinds  of  sugar,  cane  sugar 
and  beet  sugar,  were  equally  valuable  for  canning  and  identical  in 
their  behavior  when  of  the  same  fineness  of  crystallization. 

Beet  Sugar  Cannot  be  Detected  From  Cane  Sugar. — While 
the  raw  sugar  from  the  two  different  sources,  the  sugar  cane  and 
the  sugar  beet,  takes  on  the  character  of  the  impurities  from  which 
it  has  not  yet  been  freed  (the  raw  product  of  the  sugar  cane  is 
pleasant  in  flavor,  the  raw  product  from  the  sugar  beet  is  acrid  and 
disagreeable  in  flavor),  the  sucrose  or  so-called  pure  cane  sugar, 
can  be  and  is  crystallized  out,  and  in  every  case  the  sugar  is  identical 
in  chemical  composition,  appearance  and  properties.  "By  no  chem- 
ical test  can  the  pure  crystallized  sugar  from  these  two  different 
sources  be  distinguished. "- 

Quality  of  the  Sugar. — Since  the  sugar,  sucrose,  is  added  for 
the  purpose  of  preserving  the  condensed  niilk,  it  is  obvious  that  none 
but  the  best  quality  of  refined  sucrose  is  admissible.  Low  grade 
sucrose  is  a  product  dangerous  to  the  condensed  milk  business.  It 
is  apt  to  contain  sufficient  quantities  of  acid  and  invert  sugar,  to  give 
bacteria  and  yeast  an  opportunity  to  start  fermentation.  When 
once  started,  the  destruction  of  the  product  is  almost  inevitable.  In 
years  of  failure  of  the  .sugar  cane  crop,  when  the  prices  of  sucrose 
soar  high,  condenseries  yield  frequently  to  the  temptation  of  buying 
lower  grades  of  sugar.  The  result  invariably  is  an  abnormally  large 
output  of  condensed  milk  that  "goes  wrong." 

It  is  very  important  that  the  sugar  in  the  factory  be  stored 
where  it  will  keep  dry.  Sucrose  has  hygro.scopic  properties.  When 
exposed  to  an  atmosphere  saturated  with  moisture  it  absorbs  water. 
In  damp  storage  it  is  prone  to  become  lumpy,  moldy  and  frequently 
sour.  When  these  precautions  are  neglected  there  is  danger  of  de- 
fective condensed  milk,  causing  the  cans  on  the  market  to  swell,  due 
to  gaseous  fermentation. 


1  California  Agricultural  Experiment  Station,  Circular  No.   33 

2  United  States  Department  of  Agriculture,  Farmers'  Bulletin  No. 


Condensed  Milk  and  Milk  Powder  43 

When  the  sugar  reaches  the  milk  through  a  chute  from  the 
floor  above,  the  sugar  chute  and  similar  conveyors  must  be  kept 
clean  and  dry.  The  lower  end  of  the  sugar  chute  is  usually  located 
directly  over  the  steaming  milk  in  the  well  room.  In  such  cases 
there  is  always  more  or  less  danger  of  condensation  in  the  chute  of 
the  vapors  from  the  milk  below.  This  causes  the  sugar  to  stick  to 
and  form  a  crust  on  the  inside  of  the  chute.  This  moist  crust  of 
sugar,  when  contaminated  with  bacteria,  yeast  or  molds,  is  prone  to 
start  fermenting.  When  portions  of  this  sour  criist  peel  off  and  are 
carried  into  the  milk  below,  they  may  cause  entire  batches  of  con- 
densed milk  to  spoil,  as  the  result  of  gaseous  fermentation. 

Adulteration  of  sugar  wath  foreign  admixtures  such  as  white 
sand,  white  clay,  starch,  or  lime  dust  is  rare,  and  occurs  usually  only 
in  pulverized  sugar.  For  the  detection  of  these  adulterants,  add  a 
spoonful  of  the  suspicious  sugar  to  a  glass  of  hot  water  and  stir. 
Pure  sugar  will  dissolve  completely,  while  mo"st  of  the  common  im- 
purities are  insoluble  and  will  settle  to  the  bottom. 

The  purchase  of  coarsely  granulated  sugar  is  an  effective  safe- 
guard, insuring  freedom  from  these  adulterants.  Powdered  sugar 
should  not  be  used  in  the  condensery. 

Amount  of  Sugar. — The  amount  of  sucrose  used  varies  in  dif- 
erent  countries,  with  different  manufacturing  concerns,  in  different 
factories  of  the  same  company  and  at  different  seasons  of  the  year. 
The  normal  variations  range  between  twelve  and  eighteen  pounds 
of  sucrose  per  one  hundred  pounds  of  fresh  milk.  Most  factories 
use  about  16  per  cent. 

It  is  not  advisable  to  overstep  the  limits  above  indicated.  Con- 
densed milk  serves  as  a  substitute  for  fresh  milk.  The  more  sucrose 
it  contains,  the  greater  is  the  difference  in  composition  and  proper- 
ties betw^een  the  condensed  milk  and  the  fresh  milk.  Sucrose  is  not 
as  readily  digested  as  the  other  ingredients  of  milk;  therefore,  the 
presence  of  excessive  amounts  of  cane  sugar  in  condensed  milk,  tends 
to  reduce  its  digestibility  and  its  wholesomeness  as  a  food.  Again, 
while  normal  milk  is  a  well-balanced  food  in  itself,  the  presence  of 
large  amounts  of  cane  sugar  in  it,  causes  this  equilibrium  to  be  dis- 
turbed, the  condensed  milk  being  excessively  rich  in  carbohydrates 
and  relatively  poor  in  proteids.     These  facts  are  especially  signifi- 


44  Condensed  Milk  and  Milk  Powder 

cant  where  condensed  milk  is  used  for  infant  feeding  and  by  persons 
with  weak  digestion. 

On  the  other  hand,  sweetened  condensed  milk  depends  for  its 
preservation  on  the  sucrose.  This  class  of  condensed  milk  is  not 
sterile  and  is  prevented  from  rapid  deterioration  by  the  preservative 
action  of  the  sucrose  only.  Therefore,  the  smaller  the  amount  of 
sucrose  it  contains,  the  greater  the  danger  from  the  activity  of  fer- 
ments and  the  less  it!}  keeping  quality. 

The  relative  prices  of  cane  sugar  and  of  fresh  milk  also  govern 
the  amount  of  cane  sugar  used  in  many  factories.  In  summer,  milk 
prices  are  low  and  sugar  prices  are  high,  while  in  winter  the  rela- 
tive prices  are  reversed.  Hence  there  is  a  tendency  on  the  part  of 
the  manufacturer  to  use  less  sugar  in  summer  than  in  winter. 

Again,  the  amoimt  of  cane  sugar  used,  varies  according  to  the 
kind  of  market  for  which  the  condensed  milk  is  intended.  Milk  put 
on  the  market  in  hermetically  sealed  cans  is  generally  exposed  to 
more  unfavorable  conditions  and  is  older  by  the  time  it  reaches  the 
consumer  than  milk  sold  in  barrels.  It  is  customary  to  use  about 
sixteen  pounds  of  cane  sugar  for  every  one  hundred  pounds  of  fresh 
milk  for  canned  goods,  and  about  twelve  to  fourteen  pounds  of  cane 
sugar  for  barrel  goods. 

Finally,  there  is  a  strong  tendency  in  some  localities,  for 
sweetened  condensed  milk  made  in  May  and  June  to  thicken  rapid- 
ly and  become  cheesy  with  age.  This  can  easily  be  prevented  by  the 
use  of  more  cane  sugar  in  the  milk  manufactured  during  these 
months.     (See  Chapter  XXIII  on  "Condensed  Milk  Defects") 

Mixing  the  Sugar. — The  sugar  is  added  to  the  hot  milk  before 
the  latter  enters  the  vacuum  pan.  In  some  factories  a  separate  tank 
is  provided  for  this  purpose.  Small  portions  of  the  hot  milk  are 
allowed  to  flow  into  this  tank.  To  these  the  sugar  is  added.  This 
tank  is  called  the  sugar  well.  It  is  usually  equipped  with  a  mechan- 
ical, reversible  stirrer,,  moving  to  and  fro  on  an  eccentric,  to  facilitate 
the  solution  of  the  sugar.  The  milk  from  the  heater  and  from  the 
sugar  well,  runs  into  a  tank  sunk  into  the  floor  of  the  well  room,  the 
ground  well,  from  which  the  mixed  sweetened  milk  is  drawn  into 
the  vacuum  pan.  In  other  factories  the  sugar  well  and  ground  well 
are  one  and  the  Fame  tank,  into  which  the  milk  runs  direct  from  the 


Condensed  Milk  and  Milk  Powder  45 

heater.  In  this  case  it  is  advisable  to  set  a  wire  mesh  strainer  (sixty 
to  eighty  meshes  to  the  inch)  over  the  sugar  well.  The  sugar  is 
placed  into  this  strainer,  a  little  at  a  time;  the  hot  milk  from  the 
heater  passing  into  and  through  the  strainer  dissolves  the  sugar. 
A  paddle  or  stick  should  be  used  to  stir  the  sugar  in  the  strainer. 
For  greater  convenience  and  economy  of  labor,  the  sugar  barrels 
and  scales  are  placed  on  the  floor  over  the  well  room.  The  sugar 
is  transferred  to  the  strainer  below  through  a  sugar  chute  which 
may  be  ecpipped  at  the  lower  end  with  an  adjustable  cut-off,  to  reg- 
ulate the  sugar  coming  down.  Other  factories , dissolve  their  sugar 
in  boiling  water  in  a  separate  tank,  and  draw  this  syrup  into  the 
vacuum  pan  together  with  the  hot  milk.  This  is  a  very  commend- 
able practice  as  it  minimizes  the  danger  of  undissolved  sugar  crys- 
tals to  escape  into  the  pan.  Moreover,  this  watery  syrup  can  be 
boiled  without  danger  of  giving  the  milk  a  cooked  flavor. 

CHAPTER  V 

CONDENSING 

From  the  ground  well  in  the  well  room,  the  sweetened  milk  is 
drawn  into  the  vacuum  pan,  where  it  is  condensed  under  reduced 
pressure.  The  vacuum  pan  is  usually  located  on  the  second  floor 
over  the  well  room,  or  in  the  well  room  itself,  in  which  case  it  is 
elevated  above  the  floor  six  to  eight  feet.  The  vacuum  pan  is  con- 
nected with  the  vacuum  pump  which  should  be  installed  near  the  pan. 

Description  of  the  Vacuum  Pan. — The  vacuum  pan  is  a  retort 
in  which  the  milk  is  heated  and  evaporated  in  partial  vacuum.  The 
origin  of  the  term  "pan"  has  not  been  satisfactorily  explained.  In 
the  early  and  experimental  days  of  the  manufacture  of  condensed 
milk,  the  milk  was  evaporated  in  open  kettles,  called  pans.  It  is 
probable  that  the  name  of  this  primitive  apparatus  was  passed  on 
to  the  more  perfected  machinery  now  in  use. 

The  vacuum  pans  are  constructed  of  copper,  iron,  steel  or 
bronze.  Practically  all  of  the  vacuum  pans  used  for  condensing  milk 
are  made  of  copper  throughout ;  they  are  of  various  styles  and  sizes. 
The  predominating  size  used  in  milk  condenseries  is  the  "six-foot 
pan."  By  the  term  six-foot  pan  is  meant  a  retort  measuring  six 
feet  in  diameter. 


46  Condensed  Milk  and  Milk  Powder 

There  are  two  general  types  of  vacuum  pans  on  the  market ; 
pans  that  are  relatively  wide  in  diameter  and  shallow  in  depth,  and 
pans  of  a  relatively  narrow  diameter  and  which  have  a  deep  hody. 
Both  types  are  claimed  to  have  special  advantages  by  their  respec- 
tive manufacturers,  such  as  ease  of  operation,  uniformity  of  ac- 
tion, economy  of  fuel  and  water  and  rapidity  of  evaporation.  Not- 
withstanding advertising  claims  to  the  contrary,  the  pan  that  is  wide 
and  shallow  and  has  its  heating  surface  so  arranged  as  to  take  care 


FlK.  9. 
Vacuum    pan    and   condenser 


Courtesy  of 
\rtlnir  Harris  &  Co. 


of  the  maximum  amount  of  milk  with  the  minimum  depth  of  milk 
over  the  heating  surface,  is  the  most  satisfactory.  The  wide,  shal- 
low pan  offers  a  larger  area  of  boiling  surface  and  therefore  makes 
possible  more  rapid  evaporation  than  the  narrow,  deep  pan.  In  the 
wide,  shallow  pan  the  milk  boils  more  quietly,  it  is  under  better  con- 
trol and  is  less  apt  to  he  carried  over  into  the  condenser  and  lost, 
than  in  the  narrow,  deep  pan. 

The  vacuum  pan  consists  of  four  main  parts,  namely,  the  jacket, 
the  body,  the  dome,  and  the  condenser. 


Condensed  Milk  and  Milk  Powder 


47 


The  Jacket  forms  the  bottom  of  the  pan.  The  inside  wall  is 
copper,  the  outside  cast  iron.  It  is  concave  and  in  the  case  of  a 
six-foot  pan  about  two  and  one-half  feet  deep.  It  is  equipped  with 
two  steam  inlets  and  one  outlet.  The  outlets  for  the  coils  are  also 
brought  through  the  jacket.  In  the  center  of  the  bottom  there  is 
an  opening,  two  to  three  inches  in  diameter,  for  the  discharge  of  the 
condensed  milk  and  fitted  with  two  valves  and  a  nipple  between,  to 
facilitate  the  sampling  of  the  condensed  milk. 

The  Body  or  \^apor  Belt 
represents  the  main  part  of  the 
pan.  It  is  cylindrical,  of  vary- 
ing height  and  is  equipped  with 
copper  coils  which  have  their 
outlets  through  the  jacket.  Their 
upper  ends  connect,  through  the 
body  of  the  pan,  with  the  main 
steam  line.  Most  pans  are 
equipped  with  two  to  three  coils 
located  at  different  elevations. 
Since  steam  should  be  turned 
into  the  coils  only  when  they 
are  covered  with  the  milk,  it  is 
desirable  to  have  several  short 
independent  coils  rather  than  but 
one  large  one.  This  will  give  a 
larger  range  of  the  quantity  of 
milk  that  can  be  condensed  and 
increases  the  speed  of  evapora- 
tion. The  coils  vary  in  diameter  from  about  three  to  five 
inches.  The  upper  and  outer  coils  are  the  larger  ones.  The 
diameter  and  length  of  the  coils  necessarily  vary  with  and 
are  limited  by  the  capacity  of  the  pan.  The  greater  the  total 
heating  surface,  consistent  with  easy  access  to  all  parts  of  the  jacket 
and  coils,  the  better.  Other  things  being  equal,  the  more  square  feet 
of  heating  surface,  the  less  steam  pressure,  by  the  gauge,  is  required 
to  furnish  the  necessary  heat  for  maximum  evaporation.  This  is 
important  because  high  steam  pressure  in  the  jacket  and  coils,  means 
exposure  of  the  milk  to  high  temperature,  which  is  undesirable.  The 
heating  surface  should  be  sufficient  to  make  possible  the  complete 


Fig.   10.     Vaouiim  pan 


48 


Condensed  Milk  and  Milk  Powder 


Fig.  11.     Steam  coils 

Courtesy  of  Arthur  Harris  i 


condensation  of  the  steam  in  the  jacket  and  coils.  If  the  heating 
surface  is  inadequate,  more  steam  has  to  be  turned  into  the  jacket 
and  coils,  in  order  to  secure  the  necessary  heat  for  rapid  evapora- 
tion, than  will  condense ;  free  steam  will  blow  through  and  out  of  the 

coils,  resulting  in  uneconomic 
and  wasteful  use  of  fuel,  and 
jeopardizing  the  quality  of  the 
product.  A  properly  construct- 
ed six-foot  pan  usually  has  not 
less  than  one  hundred  twenty  to 
one  hundred  thirty  square  feet 
of  heating  surface. 

Jacket    and    coils    are    con- 
nected   independently    with    the 
direct     steam     main    from    the 
boiler.     Each  connection  at  the 
pan  should  carry  a  valve  and  a 
steam  gauge  on  the  pan-side  of 
the  valve.     The  main  steam  line 
and   connections   leading  to  pan   should   be   properly   insulated   by 
proper  pipe  coverings,  in  order  to  supply  the  pan  with  as  dry  steam 
as  possible. 

The  drips  or  discharge  ends  of  the  jacket  and  coils  are  con- 
nected with  the  boiler  feed  water  tank.  If  the  pan  has  sufficient 
heating  surface  and  is  operated  properly,  the  drip  ends  of  the  jacket 
and  coils  should  discharge  warm  water  only,  and  not  free  steam. 
The  jacket  and  coils  should  be  free  at  the  drip  or  discharge  ends 
so  that  all  condensation  water  may  be  quickly  and  continuously  re- 
moved. This  is  necessary  in  order  to  make  the  most  economical 
use  of  the  steam  and  to  secure  high  efficiency  of  evaporation.  In 
order  to  guard  against  back  pressure  the  drips  may  be  equipped 
with  suitable  check  valves. 

Through  the  walls  of  the  body  of  the  pan  also  enters  the  milk 
draw  pipe.  This  pipe  connects  with  the  hot  well  and  through  it  the 
milk  rushes  into  the  pan.  Immediately  outside  of  the  pan  the  milk 
pipe  should  be  equipped  with  a  valve  to  regulate  the  inflow.  The 
size  of  the  milk  draw  pipe  and  valve,  is  governed  by  the  capacity  of 
the  pan ;  usually  two  to  three  inches  in  diameter.  Inside  of  the  pan 
the  milk  pipe  should  be  turned  down.    If  this  provision  is  not  made. 


Condensed  Milk  and  Milk  Powder 


49 


rig.   12.     Vacuum  gauge 

Courtesy  of  Arthur  Harris  &   Co. 


the  milk  shoots  straight  across  the  pan  atomizing  into  a  dense  spray, 
which  is  partly  drawn  over  into  the  condenser,  causing  loss  of  milk. 
The  Dome  rests  on  top  of  the  body  of  the  pan.  It  is  equipped 
with  a  manhole,  manhole  cover,  thermometer,  vacuum  gauge,  eye 
glasses,  lights  and  blow-down  valve,  or  vacuum  breaker.  The  man- 
hole measures  about  fourteen  to 
eighteen  inches  in  diameter.  It  is 
closed  by  a  solid  brass  cover  with 
a  well  fitting,  ground-surface 
flange.  The  cover  carries  a  five 
inch  eye  glass  or  sight-glass 
through  which  the  operator  watch- 
es the  boiling  milk  in  the  pan. 
The  stem  of  the  thermometer  is 
enclosed  in  a  brass  casing  and 
reaches  to  near  the  bottom  of  the 
pan.  Some  processors  prefer  a 
short  thermometer  which  registers 
the  temperature  of  the  vapors  instead  of  that  of  the  milk.  As  both, 
the  milk  and  the  vapors  are  subjected  to  the  same  pressure,  their 
respective  temperatures  are  the  same.  The  long-stem  thermometef, 
the  bulb  of  which  is  submerged  in  the  milk,  however, 
is  more  sensitive  and  registers  changes  of  tempera- 
ture more  rapidly,  because  the  milk  is  a  better  con- 
ductor of  heat  than  the  vapors.  The  vacuum  gauge 
connects  with  the  interior  of  the  pan,  and  indicates 
the  number  of  inches  of  vacuum.  A  mercury  col- 
umn may  be  used  in  the  place  of  the  vacuum  gauge. 
In  the  rear  of  the  dome  there  are  two  eye  glasses. 
Through  these  the  interior  of  the  pan  is  illuminated 
by  means-  of  lamps,  gas  or  electric  lights.  The  "blow 
down"  valve,  or  vacuum  breaker,  serves  to  admit 
air  into  the  pan  in  order  to  "break"  the  vacuum. 
This  is  necessary  for  readily  drawing  ofif  the  fin- 
ished condensed  milk.  It  is  further  needed  to  pre- 
vent the  contents  of  the  vacuum  pan  from  being 
drawn  over  into  the  condenser,  whenever  the  milk 
rises  above  a  safe  level. 


Fig.  13. 
Thermometer 
for  vacuum  pan 

Courtesy  of 

Taylor 

Instrument  Co. 


50 


CoxDENSED  Milk  and  Milk  Powder 


The  Condenser. — The  condenser  is  that  portion  of  the  con- 
densing apparatus  in  which  the  vapors,  rising  from  the  boihng  milk 
in  the  pan,  are  condensed  to  water.  The  condenser  is  attached  to 
the  dome  of  the  pan.  There  are  three  types  of  condensers  in  use, 
the  surface  condenser,  the  barometric  condenser  and  the  wet-vacuum 
spray  condenser. 

The  Surface  Condenser  consists  of  a  tube  cyhnder  filled  with 
brass  tubes,  mounted  on  a  receiver.  The  water  used  for  cooling 
circulates  outside  of  the  tubes  and  the  vapors  pass  through  the  tubes 

where  they  are  chilled  and  con- 
densed. This  condenser  has  the 
advantage  of  enabling  the  oper- 
ator to  note  the  amount  of  con- 
densation and  to  measure  the 
amount  of  water  actually  con- 
densed. The  receiver,  at  the  bot- 
tom of  the  condenser,  should  be 
so  arranged  that  it  can  be 
drained  at  will  and  without  in- 
terfering with,  or  retarding  the 
operation  of  the  pan. 

The  Barometric  Con- 
denser consists  of  a  vertical 
cylinder  of  iron  or  brass,  equip- 
ped with  a  spray  jet.  through 
which  the  cooling  water  enters 
the  condenser.  The  vapors  be- 
ing drawn  over  from  the  vio- 
lently boiling  milk  in  the  pan, 
are  condensed  by  passing 
through  this  spray  of  cold  water. 
This  condenser  discharges  its 
water  into  a  tight  cistern  in  the 
ground.  The  condenser  is  placed 
so  that  its  bottom  flange  is  about 
thirty-five  feet  above  the  water 
level  of  the  cistern  in  which  the 
discharge  pipe  from  the  condenser  terminates.  The  height  of 
the  condenser  depends  on  the  barometric  pressure  of  the  loca- 
tion   where    it    is    installed.      The  lower    the    altitude    and    there- 


Fig.   14.     The  surface  condenser 

Courtesy  of   Buffalo   Foundry  &  Machine  Co. 


Condensed  Milk  and  Milk  Powder  51 

fore  the  higher  the  atmospheric  pressure,  the  higher  must  the  con- 
denser be  above  the  cistern.  At  the  sea  level,  the  atmospheric  pres- 
sure sustains  a  water  column  a'bout  thirty-four  feet  high.  This 
water  column  in  the  discharge  pipe  seals  the  vacuum  and  at  the 
same  time  it  permits  the  water  from  the 
spray  and  the  condensation  water  to  es- 
cape automatically.  The  cistern  in  which 
the  water  column  terminates  should  be 
of  sufficient  size  to  hold  about  one-third 
more  water  than  the  capacity  of  the  en- 
tire length  of  the  discharge  pipe  calls 
for  and  should  have  a  large  overtiow 
into  the  sewer.  When  the  pan  is  in 
operation  and  a  uniform  vacuum  is 
maintained,  the  level  of  the  water  col- 
umn remains  constant  and  the  excess 
water  from  the  condenser  overflows 
from  the  cistern  into  the  sewer. 

The  Wet-Vacuum  Sprav  Con- 
denser consists  of  a  huge  hollow  cylin- 
der of  brass  or  iron,  usually,  but  not 
necessarily,  horizontal.  It  is  equipped 
with  a  perforated  spray-pipe  placed 
lengthwise  through  the  center  of  the 
cylinder.  The  spray  pipe  connects  at 
one  end  with  the  pipe  supplying  the 
cooling  water.  WHien  the  pan  is  in 
operation,  a  shower  oi  cold  water  is- 
sues forth  from  the  perforations  in  the 
spray  pipe  as  the  result  of  the  reduced 

Fig.    15.      Barometric    condenser  .  ^, 

Courtesy  of  prcssurc    lu    pan    and    condenser.       Ihe 

Buffalo   Foundry   &    Machine   Co.      i       .  •    •  r  ^i        i      •!•  -n 

hot  vapors  ansmg  from  the  boilmg  milk 
in  the  pan  are  drawn  over  into  the  condenser,  where  they  come  in 
contact  with  the  cold  water  spray  and  are  condensed.  The  bottom 
of  the  condenser  is  connected  with  the  suction  end  of  the  vacuum 
pump,  through  which  the  water  in  the  condenser  escapes. 

The  chief  difference  between  the  wet-vacuum  condenser  and  the 
barometric  condenser  is  that,  in  the  wet-vacuum  condenser  the  water 
from  the  condenser  passes  through  the  vacuum  pump,  while  in  the 
barometric  condenser  the  water  does  not  pass  through  the  vacuum 


52  Condensed  Milk  and  Milk  Powder 

pump,  but  goes  direct  into  the  sewer  and  the  vacuum  is  sealed  by  the 
barometric  water  column.  So  far  as  practical  experience  has  shown, 
there  is  no  material  difference  in  the  efficiency  between  these  two 
types  of  condensers.    The  water  column  of  the  barometric  condenser 

helps  somewhat  to  maintain  a 
uniform  vacuum.  It  necessi- 
tates, however,  the  installing  of 
the  pan  inconveniently  high  and 
requires  somewhat  more  exten- 
Fig.  i6.~e  wet-va«uum  spray  condenser      sivc  machinery,  than  is  the  case 

Courtesy  of  Arthur  Harris  &  Co.  ^{^{-^  thg  wCt-VaCUUm  COudeUSer. 

The  chief  difference  between  both  of  these  systems  and  the  sur- 
face condenser  is  that,  in  the  wet-vacuum  and  barometric  condenser 
the  condensed  vapors  mix  with  the  cooling  water,  while. in  the  sur- 
face condenser  the  condensed  vapors  are  collected  and  carried  off 
separately  and  without  mixing  with  the  cooling  water.  In  the  case 
of  condensing  liquids,  the  vapors  of  which  are  of  commercial  value, 
the  surface  condenser  must  be  used.  The  surface  condenser,  how- 
ever, is  of  relatively  small  capacity  and  the  cooling  water  cannot  be 
utilized  as  economically  as  in  the  case  of  the  other  systems.  Where 
large  quantities  of  vapors  are  to  be  handled  and  the  vapors  have  no 
commercial  value,  as  is  the  case  in  condensing  milk,  the  barometric 
and  wet-vacuum  condensers  are  best  suited ;  their  operation  utilizes 
the  cooling  water  more  economically. 

Care  of  the  Condenser. — In  the  operation  of  the  spray  and 
jet  condenser,  special  attention  should  be  paid  to  the  condition  of 
the  spray  pipe.  Especially,  when  the  water  used  contains  much 
organic  matter,  as  is  thecase  with  water  from  a  creek,  pond  or  lake, 
there  is  a  tendency  of  the  spray  pipe  becoming  filled  and  coated  with 
slimy  organic  matter,  causing  the  perforations  to  clog.  This  ren- 
ders the  distribution  of  the  spray  irregular  and  the  control  of  the 
pan  diiffcult.  It  causes  great  waste  of  water  because  much  of  the 
water  is  discharged  from  the  condenser  and  lost  without  coming 
into  direct  contact  with  the  vapors.  The  water  is  therefore  not 
utilized  economically  and  the  difference  between  the  temperature  of 
the  vapors  and  the  discharge  of  the  condenser  is  excessive.  In  or- 
der to  avoid  this  the  condenser  should  be  cleaned  out  thoroughly  at 
least  once  a  week,  or  oftener.  if  necessary  to  keep  the  pores  of  the 


Condensed  Milk  and  Milk  Powder 


53 


spray  pipe  free  from  obstructions.  It  is  advisable  to  install  conden- 
sers equipped  with  a  manhole  on  top  or  at  the  end,  otherwise  access 
to  the  spray  pipe  is  not  sufficiently  convenient  to  insure  frequent 
inspection  and  thorough  cleaning  by  the  average  operator. 

The  Expansion  Tank,  Catch-all,  or  Milk  Trap. — This  is  a  tank, 
frequently  installed  between  the  dome  of  the  pan  and  the  conden- 
ser. Its  purpose  is  to  collect  and  reclaim  any  milk  that  may  be  car- 
ried over  from  the  pan  and  to  prevent  its  escape  and  loss  through 
the  condenser. 

If  the  pipe  through  which  the  milk  enters  the  pan  is  turned 
down  and  its  end  is  carried  to  near  the  bottom  of  the  pan,  so  as  to 
avoid  the  formation  of  excessive 
milk  spray,  if  the  pan  is  operated 
carefully  and  if  the  milk  is  kept  at 
a  reasonably  low  level,  there  is  very 
little  danger  of  milk  being  carried 
over  into  the  condenser  in  quantities 
sufficient  to  be  of  any  consequence. 
Under  these  conditions  the  installa- 
tion of  a  special  milk  trap  between 
the  pan  and  the  condenser,  for  the 
purpose  of  collecting  the  escaping 
milk  spray  and  carrying  it  back  to 
Fig.  17.     Vacuum  pan  with  milk   the  pan,  is  therefore  an  unnecessary 

trap  and  barometric  condenser 

Courtesy    of    Arthur    Harris    &    Co.     CXpenSC. 

If  the  pan  is  small  in  comparison  to  the  amount  of  milk  to  be 
condensed,  and  if  it  is  forced  beyond  its  intended  capacity,  so  that 
the  milk  boils  up  high,  there  usually  is  considerable  loss  of  milk,  as 
indicated  by  the  foaminess  and  milky  color  of  the  exhaust  of  the 
vacuum  pump.  In  such  cases  the  mechanical  loss  of  an  average 
size  batch,  may  amount  to  several  hundred  pounds  of  milk.  In 
order  to  not  lose  this  milk,  a  milk-trap  or  catch-all  may  be  installed 
between  the  pan  and  the  condenser.  The  vapors  loaded  with  the 
milk  spray  enter  the  trap  near  the  top.  The  spray  drops  to  the  bot- 
tom of  the  trap,  while  the  vapors  are  drawn  over  into  the  condenser, 
where  they  are  condensed  as  usual.  This  trap  may  be  constructed 
of  sufficient  size  so  as  to  serve  as  a  reservoir  to  collect  all  the  milk 
that  is  carried  over,  and  at  the  conclusion  of  the  process,  the  con- 


54  Condensed  Milk  and  Milk  Powder 

tents  of  the  trap  are  drawn  from  the  bottom  and  are  condensed  with 
the  next  batch ;  or  the  bottom  of  the  trap  may  be  connected  with  the 
pan  so  that  the  milk  thus  carried  over  flows  back  into  the  pan  auto- 
matically.   In  this  case  a  small  trap  only  is  necessary. 

It  should  be  understood  that  the  milk  trap  is  only  a  remedy  and 
not  a  preventive.  Where  the  capacity  of  the  pan  is  in  proportion 
to  the  amount  of  milk  to  be  condensed,  as  it  should  be,  and  where 
the  pan  is  operated  properly,  the  trap  is  unnecessary.  The  trap  is 
an  additional  piece  of  apparatus  to  be  kept  clean.  Unless  it  is  so 
constructed  that  access  can  be  had  to  all  parts  of  its  interior  and  un- 
less it  really  is  kept  clean  at  all  times,  it  may  become  a  serious  source 
of  contamination. 

The  Vacuum  Pump. — The  vacuum  pump  is,  strictly  speaking,* 
not  a  part  of  the  vacuum  pan,  but  its  intimate  connection  with  the 

pan  makes  it  necessary  to  briefly 
consider  it  at  this  point.  The 
suction  end  of  the  vacuum 
pump  is  connected  with  the  end 
of  the  condenser  farthest  .from 
the  pan.  The  vacuum  pump 
exhausts  the  pan.  forming  a 
partial  vacuum.  There  are  prin- 
cipally two  types  of  vacuum 
pumps  used  in  the  milk  con- 
densery,  the  dry-vacuum  pump  and  the  wet-vacuum  pump.  The 
dry-vacuum  pump  is  used  in  the  factories  with  the  dry-vacuum 
system,  i.  e.,  where  the  cooling  water  and  the  condensation  water 
escape  to  the  sewer  direct  and  without  passing  through  the  vacuum 
pump,  as  is  the  case  with  the  surface  condenser  and  the  barometric 
condenser.  The  wet-vacuum  pumps  are  used  with  the  wet-vacuum 
system,  where  the  cooling  water  and  the  condensation  water  pass 
through  the  cylinder  of  the  pump.  The  dry-vacuum  pumps  have 
the  advantage  of  permitting  the  operation  of  the  machine  at  a 
higher  piston  speed  than  the  wet-vacuum  pumps  in  which  the  water 
must  be  displaced  at  the  end  of  each  stroke.  The  cylinders  of  the 
dry-vacuum  pump  are  cooled  by  water  jackets.  The  initial  cost  of 
the  dry-vacuum  pumps,  however,  is  greater  than  that  of  the  wet- 
vacuum  pumps. 


Fig.   18.     ^'a<'Ullm  pump 

Courtesy  of  Arthur  Harris  &  Co. 


Condensed  Milk  and  Milk  Powder  55 

The  efficiency  of  the  vacuum  apparatus  depends  very  largely 
on  the  vacuum  pump.  Rapid  evaporation  at  a  relatively  low  tem- 
perature necessitates  the  maintenance  of  a  high  vacuum.  The  type, 
material,  construction,  workmanship,  installation  and  operation  of 
the  vacuum  pump  should  be  such  as  to  insure  the  maximum 
efficiency. 

The  pump  should  be  placed  on  a  good  foundation  and  as  near 
the  vacuum  pan  as  practicable,  in  order  that  the  full  benefit  of  the 
vacuum  may  be  realized.  The  suction  pipe  and  all  connections  must 
be  tight.  The  suction  pipe  must  be  of  the  size  directed  by  the  man- 
ufacturer, as  short  as  possible  and  with  few  and  easy  bends.  The 
grade  of  the  suction  pipe  should  be  uniform  in  order  to  avoid  air 
pockets. 

The  water  should  be  turned  into  the  condenser  before  the 
vacuum  pump  is  started.  The  pump  should  not  run  at  a  higher 
speed  than  is  necessary  to  secure  the  required  vacuum.  Excessive 
speed  means  high  steam  consumption  and  heavy  wear  and  tear  on 
the  pump.  The  amount  of  water  supplied  to  the  condenser  should 
be  regulated  to  suit  the  requirements.  Ordinarily,  and  with  a 
vacuum  of  twenty-five  to  twenty-six  inches,  the  temperature  of  the 
condenser  discharge  should  be  about  no  degrees  F.  A  lower  tem- 
])erature  would  cause  excessive  and  uneconomic  use  of  water.  The 
basin  on  the  vacuum  cylinder  should  be  kept  filled  with  water  to 
prevent  admission  of  air  to  the  cylinder  through  the  stuffing  box,  and 
the  spray  pipe  or  jet  in  the  condenser  should  be  inspected  often  to 
make  sure  that  the  perforations  are  not  clogged.  The  stuffing  box 
of  the  cylinder  should  be  well  packed  with  a  good  quality  of  packing 
and  the  steam  cylinder  well  oiled.  Start  the  pump  slowly.  Belt 
driven  pumps,  especially  Ijliose  equipped  with  a  fly-wheel,  insure 
greater  uniformity  of  speed  than  direct-acting,  steam-driven  pumps. 
Steam-driven  pumps  should  be  furnished  with  a  high  grade  gov- 
ernor. The  vacuum  pump  should  have  a  capacity,  proportionate  to 
the  size  of  the  vacuum  pan,  amount  of  heating  surface,  steam  pres- 
sure for  boiling  and  temperature  of  condensing  water. 

Science  and  Practice  of  Evaporating  in  Vacuo. — Purpose  oe 
Condensing  in  \'Acro. — The  important  advantages  gained  by  evap- 
orating milk  under  reduced  pressure,  or  in  vacuo,  are :  economy  of 
evaporation,  rapidity  of  evaporation,  low  temperature  and  large  ca- 


56  Condensed  Milk  and  Milk  Powder 

l)acity  of  apparatus.  All  of  these  features  are  essential  in  the  suc- 
cessful condensing  of  milk. 

Rapid  evaporation  cannot  take  place  until  the  milk  is  brought 
to  the  boiling  point  and  is  kept  there  until  evaporation  is  completed. 
Under  atmospheric  pressure  and  at  the  sea  level,  the  boiling  point  of 
water  is  212  degrees  F.,  the  boiling  point  of  milk  is  very  slightly 
higher,  about  214  degrees  F.  Evaporating  of  milk  under  atmos- 
pheric pressure,  however,  is  a  relatively  slow  process,  requiring  a 
long  time,  much  fuel  and  large  apparatus.  Furthermore,  exposure 
of  the  milk  to  212  to  214  degrees  F.  long  enough  to  complete  evap- 
oration would  render  the  product  unsuitable  for  market.  The  prop- 
erties of  some  of  its  ingredients  are  altered,  the  product  would  as- 
assume  a  dark  color  and  a  marked  cooked  flavor,  as  the  result  of  the 
effect  of  heat.  All  of  these  objections  are  minimized  and  partly 
avoided  by  lowering  the  boiling  point  of  milk. 

Relation  of  Pressure  to  Boiling  Point. — The  temperature 
at  which  milk  boils  depends  on  the  pressure  to  which  it  is  exposed. 


Condensed  Milk  and  Milk  Powder 


57 


The  table  below  shows  the  boiling  point  of  water  at  pressures 
ranging  from  atmospheric  pressure  at  the  sea  level  (14.72  pounds 
per  square  inch)  to  a  complete  vacuum. 

Boiling  Points  of  Water  at  Different  Vacua 


Absolute  pressure 
per  square  inch 

Vacuum  inches  of 
mercury  column 

Vacuum  milli- 
meters of 
mercury  column 

Temperatures 

of  boiling  point 

of  water,  F. 

Temperatures 

of  boiling  point 

of  water,  C. 

14.720 

0.00 

00 

212.00 

100.00 

14.010 

1.42 

36 

209-55 

98.5 

13-015 

3-45 

88 

205.87 

96.8 

12.015 

5-49 

139 

201.96 

94-3 

11.020 

7-52      i 

191 

197-75 

91.9 

10.020 

9-56 

243 

193.22 

89-5 

9.020 

11.60 

295 

188.27 

86.75 

8.024 

13-63 

346 

182.86 

83-7 

7.024 

^5-67 

398 

176.85 

80.5 

6.024 

17.70 

450 

170.06 

76.8 

5.029 

19.74 

502 

162.28 

72.5 

4.029 

21.78 

553 

153-01 

67.2 

3-034 

23.81 

605 

141.52 

60.8 

2.034 

25-85 

657 

126. 15 

52-3 

1.040 

27.88 

708 

101.83 

38.7 

.980 

28.00 

712 

100.00 

37-8 

-735 

28.50 

724 

90.00 

32.2 

-544 

28.89 

734 

80.00 

26.7 

.402 

29.18 

741 

70.00 

21 . 1 

.294 

29.40 

747 

60.00 

15-6 

.216 

29.56 

751 

50.00 

10. 0 

.162 

29.67 

'      754 

40.00 

4-4 

.127      I 

29.74 

756 

32.00 

By  courtesy  of  the  Buffalo  Foundry  and  Machine  Company 


58  Condensed  Milk  and  Milk  Powder 

The  pressure,  or  correctly  speaking,  the  vacuum  is  expressed  in 
terms  of  inches  of  mercury  which  the  atmospheric  pressure  sustains. 
The  mercury  column  is  not  a  direct  measure  of  the  pressure,  but  it 
shows  the  difference  between  the  atmospheric  pressure  and  the  abso- 
hite  pressure  in  the  vacuum  chamber.  The  atmospheric  pressure  at 
the  sea-level  is  14.7  pounds  per  square  inch.  It  sustains  a  mercury 
column  in  an  absolute  vacuum  of  thirty  inches  at  62  degrees  F.  and 
of  29.922  inches  at  32  degrees  F.  The  absolute  vacuum  may  be 
calculated  by  multiplying  the  atmospheric  pressure  by  the  factor 
2.04.  In  case  there  is  only  a  partial  vacuum  the  mercury  column 
sustained  is  lowered  to  the  extent  of  the  absolute  pressure  in  the 
vacuum  pan.     The  absolute  pressure  may  be  calculated  as  follows : 

AV  =  Absolute   vacuum    which    is   thirty    inches   at   the 
sea-level 
V  ^  Actual  vacuum 

P  =  Atmospheric  pressure  which  is  14.7  pounds  at  the 
sea-level 
AP  =  Absolute  pressure 
Example :     The  actual  vacuum  in  the  pan  is  25  inches  at  the 
sea-level.    What  is  the  absolute  pressure? 

I4.7X  (.30  —  25) 

30 

Relation  of  Altitude  to  Atmospheric  Pressure. — At  alti- 
tudes higher  than  the  sea-level,  the  atmospheric  pressure  is  reduced 
and  the  mercury  column  is  lowered,  though  the  absolute  pressure  in 
the  vacuum  pan  may  be  the  same.  Therefore,  in  factories  located 
at  high  altitudes  the  mercury  column  will  show  fewer  inches  of 
vacuum  at  a  given  temperature  and  with  a  given  absolute  pressure. 

The  following  tables  show  the  barometric  reading  in  inches  of 
mercury  and  the  atmospheric  pressure  in  pounds  per  square  inch  at 
different  altitudes,  and  the  altitudes  of  various  cities  in  the  United 
v^tates. 


=  2.45  pounds  of  absolute  pressure  per  sq.  inch 


Condensed  Milk  and  Milk  Powder 


59 


'Barometric  Reading  Corresponding  with  Diflferent  Altitudes 


Barometric 

reading  in 

inches  of 

mercury 

Atmospheric 
pressure  in 
pounds  per 
square  inch 

Altitude 
above  sea 
level  in  feet 

Barometric 
!    reading  in 
1      inches  of 
mercury 

Atmospheric 
pressure  in 
pounds  per 
square  inch 

Altitude 
above  sea 
level  in  feet 

30.0 

14.72 

0 

23-5 

11-54 

6412 

29.7 

14 

60 

264 

23.0 

1 1 .  30 

6977 

29-5 

14 

47 

441 

22.5 

II  .05 

7554 

29.2 

14 

35 

710 

22.0 

10.80 

8144 

29.0 

14 

23 

890 

21-5 

10.56 

8747 

28.7 

14 

II 

I  163 

21  .0 

10.31 

9366 

28.5 

13 

98 

1347 

20.0 

9.81 

10648 

28.2 

13 

86 

1625 

19.0 

9-32 

1 1994 

28.0 

13 

74 

1812 

18.0 

8.82 

13413 

27-5 

13 

50 

2285 

17.0 

8.33 

14914 

27.0 

13 

26 

2767 

16.0 

7.84 

16506 

26.5 

13 

02 

3257 

15.0 

7-35 

1 820 1 

26.0 

12 

77 

3758 

14.0 

6.86 

19996 

25-5 

12 

53      ' 

4268 

13.0 

6.37 

21891 

25.0 

'       12 

27 

4787 

12.0 

5.88 

23886 

24-5 

12 

03 

5318 

II. 0 

5-39 

25981 

24.0 

II 

78 

5859 

By  courtesy  of  the  Buffalo  Foundry 


Machine  Company 


6o 


Condensed  Milk  and  Milk  Powder 


^ALTITUDE  IN  FEET  OF  VARIOUS  CITIES  IN  THE 
UNITED  STATES 

By  Courtesy  of  United  States  Department  of  Agriculture 


Akron,  0 94° 

Albany,  N.  Y 22 

Atlanta,  Ga 1032 

Baltimore,  Md 92 

Birmingham,  Ala 600 

Boston,    Mass 16 

Buffalo,  N.   Y 583 

Burlington,  Vt 112 

Butte,  Mont 5555 

Charleston,  S.  C 12 

Chattanooga,   Tenn 672 

Chester,    Pa 22 

Chicago,    111 590 

Cincinnati,   0 49° 

Cleveland,   O.    : 582 

Dayton,  0 74° 

Denver,    Colo 5183 

Dallas,  Tex 430 

Des  Moines,  la 805 

Detroit,   Mich 588 

Duluth,    Minn 609 

Houston,  Tex 46 

Indiankapolis,  Ind 708 

Ithaca,  N.   Y 411 

Kansas  City,  Mo 750 

Knoxville,   Tenn 890 

Lexington,  Ky 955 

Little  Rock,  Ark 264 


Los  Angeles,  Cal 267 

Louisville,   Ky 453 

Memphis,  Tenn 256 

Milwaukee,   Wis 593 

Minneapolis,   Minn 812 

New   Haven,   Conn 10 

New  Orleans,  La 6 

New  York  City 54 

Oklahoma  City.  Okla 1197 

Omaha,  Neb 1016 

Philadelphia.    Pa 42 

Phoenix,    Ariz 1082 

Pittsburg,  Pa 743 

Providence,  R.  1 11 

Richmond,   Va 51 

Rochester,   N.   Y 519 

St.   Louis,  Mo 455 

Salt   Lake  City.   Utah 4238 

San  Francisco,  Cal 15 

Santa  Fe,  New  Mex 6952 

Seattle,    Wash 10 

South  Bend,  Ind 717 

Spokane,  Wash 1908 

Tampa,  Fla 15 

Washington,   D.    C 25 

Wichita,  Kan 1294 

Vicksburg,    ]\Iiss 196 


1  By  courtesy  of  the  Buffalo  Foundry  and  Machine  Company 


Condensed  Milk  and  Milk  Powder  6i 

According  to  Kent^  the  relation  of  altitude  to  atmospheric 
pressure  per  square  inch  is  as  follows : 

Altitude  Pounds  Pressure  Per  Square  Inch 

At  sea  level  14.7 

34   mile   above  sea  level  14.02 

Yz  mile  above  sea  level  13-33 

^  mile  above  sea  level  12.66 

1  mile  above  sea  level  12.02 
i^  miles  above  sea  level  11.42 
13^  miles  above  sea  level  10.88 

2  miles  above  sea  level  9.80 

"For  a  rough  approximation  we  may  assume  that  the  pressure 
decreases,  one-half  pound  per  square  inch  for  every  one  thousand 
feet  of  ascent." 

The  absolute  pressure  in  the  pan  of  a  factory  located  at 
Omaha.  Nebraska,  with  an  altitude  of  ten  hundred  sixteen  feet 
above  sea  level,  and  condensing  in  an  actual  vacuum  of  twenty-five 
inches,  would  then  be  as  follows : 

Atmospheric  pressure  =:  14.7  —  .5  =  14.2  pounds  per  square 
inch. 

Absolute  vacuum  =  14.2  X  2.04  rrz  28.97  inches. 

14.2  X  (28.97  —  25) 
Absolute  pressure   =  ^ =    1.95  pounds 

per  square  inch. 

Relation  of  Steam  Pressure  in  Jacket  and  Coils,  Water 
IN  Condenser,  Temperature  in  Pan  and  Vacuum,  to  Rapidity 
OF  Evaporation. — The  temperature  of  the  vapors  in  the  vacuum 
pan  depends  directly  upon  the  pressure  or  vacuum  under  which 
they  are  generated.  The  more  nearly  complete  the  vacuum  and 
therefore  the  lower  the  pressure,  the  lower  the  temperature,  and, 
other  conditions  being  the  same,  the  more  rapid  the  evaporation. 
The  pressure  in  turn  is  governed  by  the  capacity  of  the  vacuum 
pump,  the  tightness  of  the  joints,  the  steam  pressure  in  jacket  and 
coils  and  the  amount  and  temperature  of  the  water  in  the 
condenser. 


Mechanical  Engineer's  Pocket-book  p.  581 


62  Condensed  Milk  And  Milk  Powder 

With  a  low  capacity  vacuum  pump,  or  a  pump  running  irreg- 
ularly, or  too  slow,  or  too  fast,  and  with  leaky  joints,  the  vacuum 
will  always  be  low,  and  the  pressure  and  temperature  relatively  high. 
Under  these  conditions  the  pan  is  difficult  to  operate  and  evapora- 
tion is  slow. 

W^ith  the  above  conditions  under  control  and  properly  adjusted, 
the  temperature  and  the  rapidity  of  evaporation  depend  on  the 
steam  pressure  in  the  jacket  and  coils  and  on  the  amount  and  tem- 
perature of  the  water  used  in  the  condenser. 

Twenty-five  pounds  of  steam  pressure  in  the  jacket  and  coils 
has  been  found  to  be  about  the  maximum  that  can  safely  be  used. 
With  this  steam  pressure  the  milk  coming  in  direct  contact  with 
the  heating  surface  is  exposed  to  about  267  degrees  F.  and  there  is 
a  tendency  for  some  of  it  to  bake  or  burn  on,  which  is  undesirable. 
The  walls  of  the  jacket  and  coils  are  also  subjected  tO'  considerable 
strain,  since  they  are  surrounded  by  an  almost  complete  vacuum. 
Then  again,  if  the  pan  has  the  proper  amount  of  heating  surface 
the  capacity  of  the  condenser  and  the  water  supply  are  in  most 
cases  insufficient  to  take  care  of  and  condense  the  vapors,  arising 
from  the  boiling  milk  in  the  pan,  when  the  steam  pressure  in  jacket 
and  coils  approaches  or  exceeds  twenty-five  pounds.  In  many  in- 
stances twenty  pounds  of  steam  pressure  is  the  maximum  which 
can  be  used  to  advantage  and  most  condenseries  operate  their  pans 
with  twelve  to  twenty  pounds  of  steam  pressure  in  jacket  and  coils. 
In  the  operation  of  some  pans  not  more  than  about  five  pounds 
steam  pressure  can  be  used  in  jacket  and  coils  economically,  because 
the  use  of  more  steam  causes  the  steam  to  blow  through  and  out  of 
the  coils.  This  may  be  due  to  relatively  large  heating  surface,  or 
small  evaporating  capacity  due  to  a  small  capacity  pump  or  limited 
water  supply  to  condenser. 

The  capacity  of  tlie  condenser  used  in  milk  condenseries  is 
very  largely  dependent  on  the  water  supi)ly.  Whenever  the  con- 
denser is  forced  beyond  its  capacity,  by  using  excessive  steam  in 
jacket  and  coils,  the  vacuum  drops,  the  temperature  rises  and  the 
process  of  evaporation  is  retarded. 

The  higher  the  vacuum  the  more  rapid  the  evaporation.  A  rise 
in  the  steam  pressure  in  the  jacket  and  coils  increases  the  rapidity 
of  evaporation  only  as  long  as  enough  water  passes  through  the  con- 


Condensed  Milk  and  Milk  Powder  63 

denser  to  maintain  a  high  vacuum.  As  soon  as  the  steam  pres- 
sure in  the  jacket  and  coils  reaches  the  point  where  the  water  in  the 
condenser  fails  to  promptly  reduce  the  vapors,  the  vacuum  drops, 
the  temperature  in  the  pan  rises  and  evaporation  is  checked. 

If  the  water  supply  were  unlimited  and  the  water  available 
were  cool  (about  50  degrees  F.  or  below),  condensing  with  twenty 
to  twenty-five  pounds  of  steam  pressure  in  the  jacket  and  coils  would 
result  in  the  maximum  rate  of  evaporation  consistent  with  good 
quality  of  the  product. 

The  condensing  of  milk  requires  immense  quantities  of  water ; 
experience  has  shown  that  it  takes  from  two  to  three  gallons  of 
water  to  condense  one  pound  of  fresh  milk.  The  water  supply  is 
one  of  the  weakest  points  in  most  condenseries,  so  that  economy  of 
water  is  one  of  the  important  factors  to  be  considered.  The  steam 
pressure  in  the  jacket  and  coils  should  therefore  be  so  regulated,  as 
to  make  it  possible  to  maintain  the  maximum  vacuum  consistent 
with  reasonably  economic  use  of  water.  The  experience  of  the  best 
pan  operators  ,is  that  about  fifteen  pounds  of  steam  pressure  in  the 
jacket  and  coils  and  a  vacuum  of  twenty-five  inches  is  practically  the 
maximum  that  can  be  maintained  under  average  conditions  without 
taxing  the  usual  water  supply  beyond  its  capacity.  With  a  vacuum 
of  twenty-five  inches  the  temperature  in  the  pan  is  about  135  degrees 
P\,  the  temperature  varying  somewhat  with  the  altitude  of  the  fac- 
tory. In  some  condenseries  the  temperature  of  the  pan  is  kept  at 
150  degrees  F.  This  practice  may  economize  the  water  a  trifle 
better,  but  the  rapidity  of  evaporation  is  considerably  lower. 

Condensing  at  temperatures  lower  than  130  degrees  F.,  without 
reducing  the  steam  pressure  in  the  jacket  and  coils,  increases  the 
rapidity  of  evaporation,  but  taxes  the  water  supply  beyond  the  reach 
of  most  condenseries.  So  much  water  has  to  be  used  in  the  con- 
denser that  it  is  not  used  economically,  as  is  shown  by  the  relatively 
low  temperature  of  the  water  discharging  from  the  condenser.  The 
temperature  of  the  condenser  discharge  bears  a  direct  relation  to 
the  temperature  of  the  vapors  in  the  pan.  Ob.servations  made  in 
various  factories  and  under  different  conditions  by  Hunziker  and 
others  showed  that  the  condenser  discharge  was  anywhere  from  5  to 
25  degrees  F.  lower  in  temperature  than  the  vapors  in  the  pan.  the 
difference  averaging  about  15  degrees  F. 


64  Condensed  Milk  and  Milk  Powder 

The  smaller  the  difference  in  temperature  between  the  con- 
denser discharge  and  the  vapors  in  the  pan,  the  more  economic  is 
the  use  of  the  water  and  vice  versa.  It  is  not  advisable  under  aver- 
age conditions,  to  so  operate  the  pan  that  the  temperature  of  the 
condenser  discharge  drops  below  no  degrees  F.,  because  of  the 
wasteful  use  of  water  under  such  conditions. 

The  condensing  of  one  pound  of  milk  requires  about  one  pound 
of  steam  and  eighteen  to  twenty-five  pounds  of  water.  The  quan- 
tity of  heating  steam  used  for  condensing  in  vacuum  is  practically 
the  same  as  that  required  by  evaporating  in  open  pans.  In  order  to 
use  the  steam  economically  the  pan  should  be  so  operated  as  to  make 
possible  its  complete  condensation  by  the  time  it  leaves  the  jacket 
and  coils.  Whenever  so  much  steam  is  used  that  it  blows  through 
and  out  of  the  jacket  and  coils  without  being  condensed,  there  is 
great  waste  of  fuel.  For  further  details  on  this  point  see  Chapter 
y,  on  the  "Description  of  the  X'acuum  Pan." 

Starting  the  Pan. — Before  drawing  the  milk  into  the  pan,  the 
pan  should  be  thoroughly  rinsed  with  water,  then  steamed  until  the 
temperature  rises  to  about  i8o  degrees  F.  Then  the  manhole  cover 
is  put  in  place,  all  the  air  valves  are  closed,  water  is  turned  into  the 
condenser  and  the  vacuum  pump  is  started.  When  the  vacuum 
gauge  shows  over  twenty  inches  of  vacuum,  the  pan  is  ready  for 
the  milk. 

Operating  the  Pan. — The  valve  of  the  milk  pipe  leading  to  the 
pan  is  now  partly  opened.  The  milk  enters  the  pan  automatically 
as  the  result  of  the  reduced  pressure  in  the  pan.  When  the  milk 
covers  the  jacket,  steam  is  gradually  turned  into  the  jackei..  As  each 
coil  becomes  submerged  in  milk,  the  coils  are  charged  with  steam. 
At  no  time  should  steam  be  turned  on  the  jacket  and  coils  when 
thev  are  not  completely  covered  with  milk,  as  such  action  would 
cause  the  milk  to  stick  to  and  burn  on  the  heating  surface,  the  milk 
would  assume  a  burnt  flavor,  it  would  become  permeated  with 
black  specks  and  the  evaporation  would  be  retarded.  On  the  start, 
but  a  few  pounds  of  steam  pressure  should  be  used  in  the  jacket  and 
coils,  to  avoid  burning,  owing  to  the  presence  in  the  milk  of  consider- 
able air.  As  the  milk  becomes  more  concentrated  and  settles  down  to 
■  uniform  boiling,  the  steam  pressure  may  be  gradually  increased  until 
it  reaches  the  maximum.    The  maximum  pressure  permissible  must 


Condensed  Milk  and  Milk  Powder  65 

be  governed  by  the  amount  of  heating  surface,  the  capacity  of  the 
vacuum  pump  and  the  temperature  and  amount  of  water  available 
for  use  in  the  condenser.  Under  average  conditions  about  fifteen 
to  twenty  pounds  of  steam  pressure  may  be  safely  used. 

During  the  early  stages  of  the  process,  when  the  milk  is  of 
low  density,  the  evaporative  duty  is  high,  probably  about  twenty-five 
to  thirty-five  pounds  per  square  foot  of  heating  surface  with  ten 
pounds  of  steam  pressure.  This  gradually  decreases  and  is  lowest 
toward  the  end  of  the  process. 

When  enough  milk  is  in  the  pan  to  completely  cover  the  jacket 
and  coils,  the  milk  intake  should  be  reduced  and  regulated  in  ac- 
cordance with  the  rate  of  evaporation.  The  milk  is  drawn  into  the 
pan  continuously,  but  only  as  fast  as  it  evaporates.  It  should  be 
kept  as  much  as  possible  at  a  constant  level,  and  this  level  is  pref- 
erably as  low  as  is  'consistent  with  complete  covering  of  the  upper 
coil. 

In  order  to  secure  maximum  rapidity  of  evaporation,  the 
vacuum  pump  should  run  at  the  proper  speed  and  its  operation 
should  be  uniform,  a  uniform  vacuum  and  temperature  should  be 
maintained,  and  the  milk  should  be  prevented  from  rising  to  an  ab- 
normally high  level  in  the  pan. 

Prevention  of  Accidents. — The  operator  should  pay  strict  at- 
tention to  the  i)an  in  order  to  avoid  loss  of  milk  due  to  accidents. 
He  should  watch  the  water  supply  and  govern  its  use  accordingly. 
If  the  water  supply  becomes  exhausted,  air  is  liable  to  be  drawn 
into  the  pan  through  the  condenser.  This  will  cause  the  milk  to  drop 
suddenly  and  then  rise  in  a  body  threatening  to  escape  through  the 
condenser.  Whenever  air  in  considerable  quantities  is  allowed  to 
enter  the  pan  while  in  operation,  be  it  as  the  result  of  lack  of  water, 
or  through  any  other  cause,  the  escape  of  milk  may  be  avoided  by 
immediately  shutting  the  steam  inlet  to  the  jacket  and  coils,  by  clos- 
ing the  mjlk  intake  and  by  slightly  opening  the  blow-down  valve, 
whenever  the  milk  rises  dangerously  high.  By  careful  manipula- 
tion until  the  milk  again  settles  down  to  uniform  boiling,  loss  can 
be  avoided  and  the  process  can  be  continued  in  the  normal  way. 

By  the  time  all  the  milk  is  in  the  pan,  condensation  is  nearly 
completed,  and  from  ten  to  twenty  minutes  further  boiling  usually 
gives  the  milk  the  desired  density.     Toward  the  end  of  the  process 


66  Condensed  Milk  and  Milk  Powder 

the  steam  pressure  in  jacket  and  coils  should  be  reduced  to  about 
five  pounds  or  less.  When  the  milk  approaches  the  desired  density, 
it  is  comparatively  heavy  and  viscous  and  boils  less  vigorously.  ■  It 
therefore  is  more  directly  exposed  to  the  heating  surface.  In  the 
case  of  excessive  steam  pressure,  its  quality  is  jeopardized.  If  the 
batch  is  small  so  that  the  level  of  the  milk  drops  below  some  of  the 
coils,  steam  to  the  exposed  coils  .should  be  turned  off  entirely. 

CHAPTER  Vl 

STRIKING  OR  FINISHING  THE  BATCH 

Definition. — When  the  boiling  milk  in  the  vacuum  pan  ap- 
proaches the  desired  degree  of  concentration,  the  batch  is  "struck." 
The  term  "striking"  is  applied  to  the  operation  of  sampling  the  con- 
densed milk  and  testing  the  sample  for  density.  This  term  very 
probably  referred,  originally,  to  the  meaning  of' "striking  the  batch 
right,"  that  is,  stopping  the  process  at  the  proper  time,  or  when 
the  milk  is  neither  too  thick  nor  too  thin.  It  then  expressed  the 
result  of  the  operation,  while  now  it  is  used  to  mean  the  operation 
itself. 

Ratio  of  Concentration. — Sweetened  condensed  milk  intended 
for  canned  goods  has  a  specific  gravity  of  1.28  to  1.30.  This  den- 
sity is  reached  usually  when  the  ratio  of  concentration  is  about  2.5  :i, 
i.  e.,  2.5  parts  of  fresh  milk  are  condensed  to  one  part  of  condensed 
milk,  assuming  that  about  sixteen  pounds  of  sucrose  have  been  add- 
ed to  every  one  hundred  pounds  of  fresh  milk. 

Methods. — To  know  just  when  the  proper  degree  of  concen- 
tration has  been  reached,  is  difficult  and  requires  experience.  It  is 
here  where  the  processor  can  easily  make  or  lose  his  wages.  There 
are  various  indications  reminding  the  observant  processor  that  the 
milk  in  the  retort  is  nearly  "done,"  viz.,  time  consumed  for  conden- 
sing, time  elapsed  since  all  the  milk  has  been  "drawn  up,"  amount 
of  condensed  milk  left  in  the  pan,  and,  most  of  all,  the  appearance 
and  behavior  of  the  boiling  milk  itself.  Milk  that  has  been  suffic- 
iently condensed  assumes  a  glossy,  glistening  luster,  it  boils  over 
from  the  periphery  towards  the  center,  forming  a  small  nucleus  or 
puddle  of  foam  in  the  center  of  the  pan.     An  experienced  and  ob- 


Condensed  Milk  and  Milk  Powder  67 

servant  operator  knows  within  a  few  minutes,  when  the  milk  is  con- 
densed enough.  This  does  not  mean,  however,  that  he  should  wait 
until  the  last  minute  before  he  "strikes"  the  batch,  for  even  the  most 
skillful  and  experienced  processors  are  easily  deceived  by  the  mere 
appearance  of  the  condensed  milk  through  the  eye-glass. 

The  degree  of  concentration  may  be  more  accurately  determined 
by  taking  a  sample  from  the  pan  and  testing  it  by  various  methods, 
such  as  by  weighing  a  definite  quantity  of  condensed  milk  on  a  sen- 
sitive scale,  by  the  use  of  a  resistance  apparatus,  or  by  the  use  of  a 
specially  constructed  hydrometer.  Of  these  the  Ueaume  hydrom- 
eter has  been  found  the  most  suitable  to  use. 

Mechanical  devices  and  methods,  such  as  the  above,  can  be 
depended  on,  when  all  the  conditions  influencing  the  specific  gravity 
of  the  liquid  are  under  control,  and  when  there  is  plenty  of  time 
for  their  manipulation.  When  the  boiling  and  rapidly  evaporating 
milk  in  the  retort  is  approaching  the  proper  density,  however,  quick 
action  is  essential.  One  minute  over  or  under  condensing,  may  cause 
the  milk  to  be  either  too  thick  or  too  thin  for  the  market  and  may 
necessitate  the  "re-running"  of  the  entire  hatch.  These  instruments 
are,  therefore,  practically  worthless  at  the  time  they  are  needed 
most.  There  is  not  time  to  carefully  measure  and  weigh  out  a  sam- 
ple of  sweetened  condensed  milk,  nor  can  the  processor  always  wait 
until  the  hydrometer  has  found  its  equilibrium  in  as  viscous  a  fluid 
as  sweetened  condensed  milk.  Again,  the  density  or  specific  grav- 
ity of  the  finished  product  depends,  outside  of  the  degree  of  con- 
centration, on  many  and  fluctuating  conditions,  such  as  amount  of 
heat  applied  toward  the  end  of  the  process,  the  temperature  of  the 
sample  when  drawn,  and  the  per  cent,  of  fat  and  cane  sugar  in  the 
condensed  milk.  It  is  for  these  reasons  that  arbitrary  mechanical 
instruments  and  methods  are  not  uniformly  satisfactory,  and  are 
prone  to  yield  misleading  results.  The  experienced  eye  and  good 
judgment  of  the  processor  are  all  essential.  The  following  are  sat- 
isfactory and  reliable  methods  of  "striking,"  which,  with  a  little 
experience,  enable  the  operator  to  determine  the  proper  degree  of 
condensation : 

Draw  a  sample  from  the  pan  into  a  tin  dipper,  lower  the  dipper 
into  a  pail  of  ice  water  or  snow.  Stir  the  condensed  milk  with  a 
metal-back  thermometer  until  the  condensed  milk  is  cooled  to  70 


68 


Condensed  Mii^k  and  Mii^k  Powder 


11! 


¥ 


FiK-  !!»■    Beau  me 
hydrometer  for 

sweetened 
condensed  milk 

Courtesy 

C.   J.   Tagliabue 

Mfg.   Co. 


degrees  F.  Note  the  thickness  of  it ;  or,  finish  the  batch 
at  a  constant  temperature,  say  120  degrees  F.  Draw 
a  sample  into  a  tin  cup  and  note  the  thickness  by  exam- 
ining the  milk  when  pouring  from  a  teaspoon.  The 
transparency  of  the  milk  when  thus  held  against  the 
light  is  a  good  indication  of  its  density.  The  last 
method  is  preferable  because  of  its  greater  rapidity. 

Use  of  Beau  me  Hydrometer. — Beginners  and 
inexperienced  operators  do  well  to  take  numerous  sam- 
ples from  the  batch  in  the  operating  pan  and  to  start 
sampling  early,  so  as  to  avoid  over-condensing.  The 
use  of  a  Beaume  hydrometer,  especially  constructed 
for  sweetened  condensed  milk,  graduated  from  30  to 
2)"/  degrees  B.  and  with  subdivisions  of  one-tenth  de- 
grees, is  an  additional  safeguard  to  insure  accuracy 
and  uniformity  of  thickness.  No  definite  figure  at 
which  the  Beaume  hydrometer  should  be  read  can  be 
-Stated,  that  would  show  the  proper  density  under  all 
conditions.  The  Beaume  reading  of  sweetened  con- 
densed milk  of  the  proper  concentration  varies  with 
such  factors  as  per  cent,  of  fat,  per  cent,  of  sucrose 
and  per  cent,  solids,  ratio  of  concentration,  and  tem- 
perature of  the  condensed  milk  when  the  reading  is 
taken.  However,  for  general  guidance,  it  may  be 
stated  that  condensed  milk  of  proper  density,  made 
from  fresh  milk  of  average  richness,  and  containing 
sucrose  at  the  ratio  of  sixteen  pounds  of  sugar  per 
one  hundred  pounds  of  fresh  milk,  will  show  a  Beaume 
reading  of  about  33.5  degrees  B.  at  60  degrees  F,,  or 
about  32  degrees  B.  at  120  degrees  F.  Sweetened  con- 
densed skim  milk,  containing  approximately  40  per 
cent,  sucrose  will  show  a  Beaume  reading  at  60  de- 
grees F.  of  about  37  degrees  B.,  or  about  35.5  degrees 
B.  at  120  degrees  F. 

Correction  of  Hydrometer  Reading  for  Tem- 
perature.— The  Beaume  hydrometers  used  in  Ameri- 
can condenseries  are  graduated  to  give  correct  read- 
ings at  60  degrees  F.  If  the  readings  are  to  be  correct, 
or  if  it  is  desirable  to  convert  them  into  specific  grav- 


Condensed  Milk  and  Miek  Powder  69 

ity,  the  condensed  milk  should  have  a  temperature  of  60  degrees  F. 
Where  this  is  not  convenient,  the  observation  may  be  made  at  any 
temperature  convenient  and  the  reading  corrected  as  follows : 

When  the  temperature  is  above  60  degrees  F.  multiply  the  dif- 
ference between  the  observed  temperature  and  60  degrees  F.  by  the 
factor  .025  and  add  the  product  to  the  observed  reading  of  the 
Beaume  hydrometer.  When  the  temperature  of  the  observed  read- 
ing is  below  60  degrees  F.  the  corresponding  product  is  deducted: 

Example:  Beaume  reading  at  120  degrees  F.  is  31.2.  Correct- 
ed reading  is  31.2  +  [.025  x  (120  —  60)]  =  32.7.  The  specific 
gravity  may  be  calculated,  when  the  Beaume  feading  is  known,  by 
using  the  following  formula : 

144-3 

Specific  gravity  =  — - ;  B.  =  Beaume  reading 

144-3  —  ^' 

Example:     Beaume  reading  at  60  degrees  F.  is  33.1. 

144.3 

Specific  gravity  = =  1.2076 

144-3  — 33-1  ^^ 

In  the  following  table  are  assembled  figures  showing  the  spe- 
cific gravity  of  sweetened  condensed  milk  of  different  Beaume  de- 
grees, varying  from  28  degrees  B.  to  37.8  degrees  B. 


70 


Condensed  Milk  and  Milk  Powder 


SPECIFIC  GRAVITY  OF  SWEETENED  CONDENSED  MILK 
OF  DIFFERENT  BEAUMfi  DEGREES 


Beaume  at 

Specific 

Beaume  at 

Specfllc 

«0  degrees  F. 

Gravity 

60  degrees  F. 

Gravity 

28.0 

1.2407 

33-0 

1.2965 

_2 

1.2428 

.2 

1.2988 

•4   ■ 

1.2449 

•4 

I. 301 1 

.6 

.1.2471 

.6 

1-3034 

.8 

1-2493 

.8 

I  -  3058 

29.0 

1-2515 

34-0 

1.3082 

_2 

1-2536 

,  2 

I. 3106 

•4 

1-2558 

-4 

I -3130 

.6 

1.2580 

.6 

I-3154 

.8 

I . 2602 

.8 

I. 3178 

30.0 

I . 2624 

35-0 

I . 3202 

.2 

I . 2646 

.2 

I . 3226 

•4 

1.2668 

•4 

1-3250 

.6 

I . 2690 

.6 

1.3274 

.8 

I. 2713 

.8 

1.3299 

31.0 

1.2736 

36.0 

1-3324 

2 

1.2758 

_  2 

1-3348 

•4 

I . 2780 

•4 

1-3372 

.6 

1.2803 

.6 

.  1-3397 

.8 

I . 2826 

.8 

1.3422  • 

32.0 

1.2849 

37-0 

I  -  3447 

.2 

I . 2872 

2 

1-3472 

•4 

1.2895 

-4 

1-3497 

.6 

I .2918 

.6 

I • 3522 

.8 

I. 2941 

.8 

1.3548 

Condensed  Milk  and  Milk  Powder 


71 


Sampling  oe  Batch. — The  samples  can  be  drawn  from  the  pan 
by  operating  the  two  valves  at  the  bottom.  While  the  milk  is  con- 
densing, the  partial  vacuum  in  the  pan  makes  impossible  the  draw- 
ing off  of  the  sample  by  simply 
opening  the  outlet.  Instead  of  caus- 
ing the  milk  to  come  out,  air  would 
rush  in  with  violent  force  arid 
would  cause  the  milk  in  the  pan  to 
be  thrown  over  into  the  condenser, 
besides  dangerously  jolting  the  ma- 
chinery. For  this  reason,  the  outlet 
is  equipped  with  two  valves,  both 
of  which  are  closed  during  the  con- 
densing process.  For  taking  sam- 
ples, open  the  upper  valve.  This 
allows   the  condensed  milk  to   run 


rigf.  20.  A     con- 
venient  device  ,  .       ,        , 

for  sampling:     mto    the    nipple    between    the    two 

the  condensed  . 

milk   in  the   pan   ValVC 

Anhur' Harris    ''^^^^  ^P^"  ^hc  lowcr  ouc.    The  milk 

&   Co.  ^yi]l 


Now  close  the  upper  valve 


Fig.  21.     A  convenient 

device  for  Hampling 

condensed  milk 

in  tlie  pan 

Courtesy    of 
Arthur   Harris  &  Co. 


run    out    freely.      The    first 
sample  should  be  rejected,  as  it  may  contain  water  caught  in  the 
nipple.      For    greater    convenience,    specially    constructed    sample 
testers  attached  to  the  side  of  body  of  the  pan  may  be  used. 

Drawing  off  the  Condensed  Milk. — As  soon  as  the  evaporation 
is  completed,  the  steam  is  shut  off  from  the  jacket  and  coils,  the 
water  valve  is  closed,  the  vacuum  pump  stopped  and  the  vacuum 
broken  by  opening  the  "blow-down"  valve.  The  manhole  cover  is 
then  removed  and  the  vacuum  pump  started  again  in  order  to  re- 
move the  hot  air  over  the  milk.  The  milk  is  drawn  into  40-quart 
cans.  The  condensed  milk  should  be  drawn  from  the  pan  as  rap- 
idly as  possible  to  prevent  its  superheating  while  in  the  pan.  In 
some  factories  a  wire  mesh  or  cloth  strainer  is  attached  to  the  out- 
let of  the  pan,  so  that  the  condensed  milk  is  strained  before  it  runs 
into  the  cans.  This  practice  is  unnecessary  and  objectionable,  as  it 
tends  to  retard  the  removal  of  the  milk  from  the  pan. 


COOLING 

The  condensed  milk  in  the  40-quart  cans  has  now  a  tempera- 
ture of  about  115  degrees  F.  to  130  degrees  F.     If  it  were  allowed 


72  Condensed  Milk  and  Milk  Powder 

to  cool  naturally,  i.  e.,  if  no  effort  were  made  to  cool  it  promptly, 
it  would  become  thick  and  cheesy  in  texture  in  a  short  time.  It  is, 
therefore,  essential  that  it  be  cooled  at  once.  Formerly,  this  was 
done  by  setting  the  cans  in  tanks  containing  ice  water  and  stirring 
the  milk  with  a  stick.  This  was  a  very  crude  method,  it  involved 
much  hard  work  and  time,  and  the  quality  of  the  product  was  poor. 
It  was  soon  found  that  the  imperfect  hand  stirring  caused  excessive 
sugar  crystallization,  which  made  the  milk  sandy.  The  sudden  chil- 
ling and  irregular  stirring  of  a  saturated  sugar  solution  like  sweet- 
ened condensed  milk  are  favorable  to  the  formation  of  sugar  crystals. 
Where  the  stirring  is  imperfect  and  irregular,  all  the  milk  is  not 
kept  in  sufficient  motion  to  insure  uniform  and  gradual  cooling. 
The  milk  next  to  the  side  of  the  cans  is  chilled  too  abruptly, 
favoring  the  formation  of  crystals.  \'igorous  stirring  in  itself  is 
conducive  of  sugar  crystallization. 

The  hand  stirring  has  been  completely  superseded  by  mechan- 
ical stirring.  Paddles  closely  scraping  the  sides  of  the  cans  are  now 
used.  Instead  of  setting  the  paddles  in  motion,  they  are  stationary 
and  the  cans  revolve.  The  principle  is  similar  to  that  of  the  vertical 
ice  cream  freezer.  Heavy  iron  tanks,  with  a  capacity  of  twelve  to 
forty-eight  40-quart  cans,  are  used  for  this  purpose.  The  bottoms 
of  these  tanks  are  equipped  with  a  system  of  cog  wheels,  set  in  mo- 
tion by  means  of  a  gear  at  one  end  of  the  tank.  The  wheels  have  a 
diameter  large  enough  to  carry  one  can  each.  The  cans  are  set  on 
these  wheels,  the  paddles  are  inserted  and  fastened  to  cross-bars 
and  the  power  started.  The  cans  should  be  heavily  constructed  to 
stand  rough  usage,  without  suffering  indentations.  Cans  with  ir- 
regular, depressed,  or  bulged  sides  cause  the  paddles  to  do  poor 
work.  Such  cans  should  be  slipped  over  a  wooden  horn,  or  other 
contrivance,  and  the  indentations  hammered  out  with  a  mallet.  The 
paddles  are  held  stationary  'by  cross-ibars  and  are  forced  against  the 
periphery  of  the  cans  by  springs.  Attention  should  also  be  paid  to 
the  pivots  on  which  the  cog  wheels  rest.  If.  they  are  warped,  the 
wheels  do  not  run  true,  so  that  it  is  not  possible  for  the  paddles  to 
scrape  the  sides  of  the  cans  properly. 

The  sweetened  condensed  milk  should  be  cooled  gradually.  Sud- 
den chilling  should  be  avoided.  This  is  best  accomplished  by  warm- 
ing the  water  in  the  cooling  tank  to  about  90  degrees  F.,  before  the 
cans  are  set  in.     The  cans  are  then  allowed  to  revolve  for  fifteen 


Condensed  Milk  and  Milk  Powder 


73 


to  twenty  minutes  before  any  cold  water  is  turned  into  the  tank. 
After  that,  cold  water  is  turned  in  slowly  until  the  temperature  of 
the  milk  has  fallen  to  about  70  degrees  F.  The  entire  time  of  cool- 
ing should  last  about  two  hours.     The  

cans  should  revolve  slowly,  rapid  stirring 
enhances  the  precipitation  of  sugar  crys- 
tals. In  order  to  scrape  the  sides  of  the 
cans  efficiently,  when  the  cans  revolve 
slowly,  (about  five  revolutions  per  min- 
ute) it  is  advisable  to  use  two  paddles  in 
each  can,  scraping  the  cans  at  opposite 
sides.  When  the  milk  is  sufficiently 
cooled  the  cans  are  stopped,  the  paddles 
lifted  out,  scraped  and  removed,  and  the 
cans  taken  out  of  the  tank. 

In  some  factories,  the  condensed 
milk  is  transferred  from  the  pan  direct 
into  large  tanks  and  is  subsequently 
cooled  by  pumping  it  through  a  series  of  coils  submerged  in  cold 
water.  This  method  is  labor  and  time-saving  and  the  objectionable 
features  of  agitation  are  avoided.  On  the  other  hand,  there  is  dan- 
ger of  too  rapid  chilling  which  tends  toward  excessive  sugar  crystal- 
lization and  the  production  of  rough,  sandy  and  settled  milk. 


Fig.   22.     Cooling  tank  for 
sweetened  condensed  milk 

Courtesy  of  Arthur  Harris  &  Co. 


CHAPTER  VII 


FILLING 


The  sweetened  condensed  milk  is  put  on  the  market  in  barrels 
and  in  hermetically  sealed  tin  cans. 

In  Barrels. — l>arrels,  similar  to  glucose  barrels,  are  generally 
used.  They  hold  from  three  hundred  to  seven  hundred  pounds  of 
condensed  milk.  New  barrels  should  be  used  for  this  purpose. 
Barrels  paraffined  on  the  inside  are  most  satisfactory,  as  they  are 
more  apt  to  be  free  from  mold  spores.  Old  glucose  barrels  are 
dangerous  to  use,  as  they  often  contain  decaying  remnants  of  glu- 
cose, which  cause  the  condensed  milk  to  ferment.  The  new  barrels 
are  steamed  out  and  drained  thoroughly.  The  filling  is  facilitated 
by  the  use  of  a  large  galvanized  iron  funnel  with  a  discharge  one 


74 


Condensed  Milk  and  Milk  Powder 


and  one-half  inches  in  diameter,  or  an  orchnary  milk  pail  with  a 
nipple  one  and  one-half  inches  in  diameter  in  the  bottom  of  the  pail. 
When  filled,  a  double  layer  of  cheese  cloth  is  placed  over  the  bung- 
hole,  and  the  bung  is  driven  in  level  with  the  staves.  The  barrel 
goods  are  sold  to  bakeries  and  candy  factories. 

In  Cans. — ^The  canned  goods  are  intended  for  the  retail  market. 
The  cans  used  hold  from  eight  to  sixteen  ounces  of  condensed  milk. 
Most  makes  of  tin  cans  for  sweetened  condensed  milk  have  a  small 


Fig.  23.     The  >^ 


K 


Fig.  ''+■     Tl'e  (iehee  seal 


Fig.  26.     The  McDonald  seal 


opening,  three-eighths  to  three-fourths  inch  in  diameter,  through 
which  they  are  filled.  The  cans  made  by  the  Sanitary  Can  Com- 
pany are  filled  before  the  top  is  crimped  on.  Sweetened  condensed 
milk  is  of  a  semi-fluid,  viscous  and  sticky  consistency.  The  suc- 
cessful and  rapid  filling  of  the  cans  without  spilling  the  milk  over  the 
top  of  the  can  is,  therefore,  .somewhat  difficult.  If  done  by  hand 
the  work  is  very  slow.     For  this  reason  many  ingenious  machines 


Courtesy  of  The  Sprague  Canning  Machinery  Co. 


CoNDENSKD  Milk  and  Milk  Powder 


75 


Fig.  27.     The  Stickney  flUer 

Courtesy  of  The  Sprague  Canning 
Machinery  Co. 


have  been  devised  which  are  more  or  less  efficient  in  "cutting  off" 
the  milk  without  "slobbering."  The  filling  machines  now  in  use 
vary  from  the  primitive  hand  filler,  in 
which  the  condensed  milk  is  "ground 
out"  by  the  turning  of  a  crank  by  hand, 
to  the  most  perfect  forms  of  automatic 
filling  machines.  In  these  filling  ma- 
chines, all  parts  coming  in  contact  with 
the  condensed  milk  are  constructed  of 
brass.  They  are  equipped  with  a  reser- 
voir, receiving  tank,  or  hopper,  which  has 
an  automatic  feed,  usually  a  Boating  de- 
vice attached  to  a  valve,  which  regulates 
the  infiow  according  to  the  discharge. 
The  discharge  is  adjustable  to  fill  any 
size  can  with  a  remarkable  degree  of 
accuracy.  Machines  of  this  type  will  fill 
from  twenty-five  thousand  to  thirty 
thousand  cans  per  day  (ten  hours). 
These  machines  are  of  complex  construction  and  must  receive 
proper  care.  It  is  best  to  clean  them  thoroughly  after  each  day's 
work.  But,  since  their 
inlet  and  discharge 
are  closed  hermetic- 
ally, the  complete 
washing  may  be  done 
once  per  week  only, 
without  seriously  dis- 
turbing their  efficien- 
cy or  impairing  the 
product.  For  thor- 
ough cleaning,  t  h  e 
filler  should  be  dis- 
sected, removing  all 
detachable  parts,  such 
as  valves,   pistons, 

tube  S.       etc.        \\'hen  ^,.^    ^^      ^^^^   Merrell-Soule  filler 

freed      from      all      rem-  courtesy  of  The  Sprague  Canning   :Mathinery  Co. 


76  Condensed  Milk  and  Milk  Powder 

nants  of  condensed  milk,  the  parts  should  be  scalded,  dried  and  re- 
placed in  the  machine.  In  order  to  guard  against  all  possible  con- 
tamination by  remnants  of  wash  water,  it  is  advisable  to  reject  the 
first  few  cans  of  milk  of  the  next  filling.  When  not  in  use,  the 
filling  machine  should  be  covered  with  clean  cloth,  or  oil  cloth,  to 
protect  it  from  dust  and  flies,  etc. 

As  soon  as  the  cans  are  filled,  they  should  be  "capped."  If 
allowed  to  stand  open,  dust,  dirt  and  flies,  or  other  insects  are  prone 
to  reach  their  interior,  and  the  prolonged  exposure  of  the  condensed 
milk  to  the  air  causes  the  surface  to  crust  over. 

SEALING 

Kinds  of  Seals. — The  seal  must  be  air-tight  and  firm  enough  to 
prevent  its  breaking  during  the  rough  treatment  to  which  the  cans 
are  exposed  in  transportation.  There  are  several  methods  of  seal- 
ing the  cans,  depending  largely  on  the  construction  of  the  can.  Most 
of  the  cans  used  are  sealed  with  solder.  There  is  a  groove  around 
the  opening,  the  cap  fits  into  this  groove  and  the  latter  is  filled  with 
solder.  In  the  case  of  cans  which  are  sealed  without  solder,  the  cap 
or  the  entire  end  of  the  can  is  crimped  onto  the  can  so  as  to  make  a 
hermetical  seal.  The  McDonald  seal  with  the  friction  cap,  the  Gebee 
seal  with  the  burr  cap,  and  the  Sanitary  can  seal  with  the  top  of  the 
can  crimped  on  after  filling,  are  the  chief  types  of  solderless  seals.  In 
the  case  of  the  McDonald  seal,  a  tightly  fitting  cap  with  a  wide 
flange  is  pressed  into  the  opening.  The  "capped"'  can  passes  under 
a  series  of  steel  rollers  pressing  the  flange  firmly  against  the  top  of 
the  can.  This  seal  is  very  simple,  but  is  not  very  strong  and  not 
hermetically  tight.  In  the  case  of  the  Gebee  seal,  a  rim  projects 
around  the  opening  of  the  can.  After  the  cap  is  inserted,  it  is 
crimped  over  this  rim  by  means  of  a  series  of  revolving  dies.  This 
seal  is  reasonably  strong  but  not  hermetically  tight.  The  Sanitary 
can  is  entirely  open  at  one  end  when  filled.  The  cover  or  end  is 
crimped  around  the  periphery  of  the  body  of  the  can  by  means  of 
revolving  dies.  This  seal  is  reasonably  strong  and  usually  hermet- 
ically tight. 

The  chief  advantages  of  the  seals  without  solder  lie  in  the  sav- 
ing of  labor,  and  the  reduction  of  the  cost  due  to  the  omission  of 
solder.    The  principal  reason  for  which  they  are  not  used  more  gen- 


Condensed  Milk  and  Milk  Powder 


17 


erally  by  milk  condensing  companies,  lies  in  the  fact  that  these  sold- 
erless  seals  are  all  patented.  In  most  cases  the  inventors  or  patent 
holders  are  condensed  milk  manufacturers.  They  refuse  to  sell  their 
patents  at  a  reasonable  price  to  other  condenseries  and  they  charge 
exor'bitant  royalties  for  the  use  of  their  patents  by  their  competitors. 
With  the  possible  exception  of  the  "Sanitary  can,"  solderless  seals 
are  not  as  reliable  as  solder  seals. 

Soldering  Devices  and  Machinery. — The  sealing  of  all  solder- 
less  seals  is  done  by  specially  constructed  sealing  machines. 


Fig.   29.     Soldering;  stove 

Courtesy   of  Arthur   Harris  &   Co. 

For  seals  with  solder  there  are  sev- 
eral machines  on  the  market  but  most  of 
this  work  is  as  yet  done  by  hand.  For 
this,  different  types  of  soldering  coppers 
are  in  use  and  the  copper  tips  are  heated 
in  soldering  stoves  or  pots.  Some  sold- 
ering coppers  have  hollow  circular  tips 
with  a  diameter  equal  to  that  of  the  cap 
used.  The  hollow  tip  is  telescoped  by  a 
rod  which  holds  the  cap  in  place  and  the 
periphery  of  the  tip  fits  mto  the  groove 
of  the  opening  of  the  can,  where  it  melts 
the  solder,  completing  the  seal.  A  rapid, 
neat  and  leakless  seal  can  be  made  with 
this  instrument. 

Ordinary  soldering  coppers  with  a  blunt  point,  such  as  are  in 
general  use  by  the  tin  smith,  are  not  very  satisfactory.  Unless  they 
are  drawn  out  and  filed  down  into  a  fine  point,  their  use  is  not  con- 
ducive of  neat  work,  progress  is  comparatively  slow  and  leakers  are 
often   numerous.     When   gas   is   available   the   automatic   soldering 


Fin.  30.    A  convenient  device  for 
NolderinK  by  hand 

Courtesy  of  The  Sprague  Canning 
Machinery  Co. 


/S  Condensed  Milk  and  Milk  Powder 

copper  may  be  used  to  advantage.  In  this  tool  the  copper  tip,  which 
is  long  and  slender,  is  automatically  heated  by  a  current  of  gas  pass- 
ing through  the  handle  and  burning  at  tlie  copper  tip.  The  handle 
of  the  device  is  connected  with  the  gas  and  air  pipes  by  means  of 
flexible  rubber  tubing.  No  tinte  is  lost  waiting  for  the  coppers  to 
heat  and  the  flame  can  be  so  regulated  that  the  temperature  of  the 
copper  tip  is  right  and  uniform.  This  is  important,  because  perfect 
work  is  impossible  unless  the  coppers  have  the  proper  temperature. 

Machine-soldering  is  now  gradually  replacing  hand-soldering. 
The  principle  of  the  older  types  of  .soldering  machines  consisted  of 
revolving  discs  on  which  the  tin  cans  were  placed.  The  cap  was 
held  in  place  by  a  vertical  rod  pressing  on  it.  The  solder  was  ap- 
plied by  hand,  the  hot  soldering  copper  was  held  over  the  groove 
in  the  can  while  the  cans  revolved.  This  method  had  no  particular 
advantage  over  the  hand  soldering.  There  was  little,  if  any.  saving 
of  time  and  the  quality  of  the  work  was  not  much,  if  any.  better. 

There  are  now  on  the  market  newer  types  of  soldering  machines, 
most  ingeniously  constructed  and  their  operation  in  factories  with 
large  outputs  economize  labor  and  time.  When  operated  by  a  skillful 
mechanic  they  do  very  creditable  work. 

Solder. — The  solder  used  for  sealing  should  be  of  standard 
composition.  In  this  country,  canning  establishments  are  prone  to 
use  a  very  poor  quality  of  solder.  It  contains  from  45  to  55  per 
cent.  lead.  Lead  is  a  poisonous  metal;  its  use  in  the  canning  indus- 
try should,  therefore,  be  regulated  by  law.  In  Germany,  the  law 
requires  that  solder  used  in  tin  cans  for  food  products  must  not  con- 
tain over  10  per  cent,  of  lead. 

W'here  the  sealing  is  done  by  hand  the  solder  is  most  conveniently 
used  in  the  form  of  thin  bars  or  wire.  The  wire  is  usually  bought 
already  cut  up  in  segments,  each  segment  furnishing  solder  enough 
to  seal  one  can.  In  the  newer  types  of  soldering  machines  the  solder 
wire  is  automatically  fed  from  spools.  The  smaller  the  opening  of 
the  can,  the  less  solder  is  necessary  to  complete  the  seal.  An  opening 
smaller  than  three-eighths  of  an  inch  in  diameter,  however,  camiot 
conveniently  be  used,  owing  to  the  difficulty  of  filling  the  can  with 
this  viscous  product.  The  essential  points  of  satisfactory  sealing 
are:  no  "leakers,"  neat  work,  rapid  work,  small  amount  of  solder. 
Aside  from  the  size  of  the  opening  of  the  can,  the  amount  of  solder 
used  depends  on  the  experience  of  the  sealer.     r)eginners  usually 


Condensed  Milk  and  Milk  Powder 


79 


'■Ul»i! 


m^ 


I 


make  an  uneven  seal,  waste  much 
solder,  and  have  many  "leakers."  This 
is  largely  due  to  their  ignorance  of  the 
proper  soldering  temperature  of  the 
coppers.  An  experienced  sealer  will 
use  from  two  to  three  pounds  of 
solder  per  thousand  tin  cans  with 
moderate-sized  openings.  He  will  seal 
from  fifteen  hundred  to  twenty-five 
hundred  cans  per  day. 

Soldering  Flux. — The  use  of 
solder  requires  the  application  of 
soldering  flux,  to  prepare  the  surface 
of  the  tin  for  the  solder.  The  flux 
always  precedes  the  solder.  When 
the  hot  solder  is  applied,  some  of  the 
flux  is  bound  to  sweat  through,  be- 
tween cap  and  can,  gaining  access  to 
the  interior  of  the  can.  The  common 
practice  of  using  zinc  chloride  or  other 
similar  acid  fluxes,  which  are  highly 
poisonous,  therefore,  cannot  be  too 
strongly  condemned.  Their  presence 
in  the  can  may  jeopardize  the  health 
and  life  of  the  consumer,  as  well  as 
the  marketable  properties  of  the  prod- 
uct. There  are  other  fluxes  which 
are  absolutely  harmless,  and  which,  if 
properly  used,  give  satisfactory  re- 
sults. Dry,  powdered  resin,  or  resin 
dissolved  in  alcohol  or  gasoline,  are  of 
this  class.  Ammonium  chloride,  while 
used  in  most  tin  shops,  is  not  as  well 
suited  for  this  puri)ose. 

Gas  Supply. — A  plentiful  and 
steady  supply  of  gas  is  very  essen- 
tial. Where  natural  gas  or  gas  from 
a  municipal  corporation  is  not  avail- 


8o  Condensed  Milk  and  Milk  Powder 

able,  the  factory  must  rely  on  its  own  generator.  For  the  needs 
of  the  condensery  a  gasoline  gas  plant  seems  suitable.  Gaso- 
line gas  is  produced  by  forcing  atmospheric  air  over  or  through  a 
body  of  gasoline.  The  mixture  of  air  and  gasoline  vapors  forms  the 
gasoline  gas.  The  gas  generators  in  use  consist  chiefly  of  carbu- 
retor, air  pump  or  blower,  and  regulator.  The  carburetor  usually  has 
a  series  of  cells,  connected  with  one  another  by  means  of  a  system  of 
syphon  tubes.  The  interior  of  each  cell  is  partitioned  off  with  heavy 
cotton  wicking.  This  wicking  absorbs  the  gasoline  by  capillary  at- 
traction. The  air,  passing  through  the  fine  meshes  of  wicking,  comes 
in  contact  with  a  large  surface  of  gasoline. 

The  following  are  some  of  the  essential  points  to  be  observed 
in  the  installation  and  operation  of  gas  generators  of  this  type :  Sink 
the  carburetor  low  enough  (three  to  five  feet  below  the  surface  of  the 
ground,  if  necessary)  to  permit  the  gas  pipe  to  slant  from  the  factory 
to  the  carburetor.  If  the  gas  pipe  is  horizontal,  or  inclined  toward 
the  factory,  condensation  water  may  collect  in  the  pipe,  obstructing 
the  free  passage  of  gas.  This  causes  the  gas  either  not  to  be  avail- 
able at  all,  or  to  reach  the  stoves  in  irregular  gusts,  which  is  equally 
unsatisfactory.  Where  the  gas  pipe  slants  toward  the  carburetor, 
the  condensation  water  flows  back  into  the  carburetor,  causing  no  ob- 
struction. Use  gasoline  of  the  best  quality  only.  Cheap  grades  form  a 
residue  and  clog  the  generator.  The  gasoline  is  best  bought  in  iron 
barrels ;  this  prevents  unnecessary  loss  by  evaporation,  which  occurs 
in  wooden  barrels,  especially  in  summer.  The  cells  should  not  be 
filled  more  than  two-thirds  full ;  too  much  gasoline  reduces  the  gas- 
generating  caipacity  of  the  carburetor.  If,  during  extremely  cold 
weather,  the  carburetor  refuses  to  generate  gas,  the  injection  of  a 
pint  of  wood  alcohol  through  the  blow  pipe  into  the  cells,  usually 
remedies  the  trouble.  The  gas  plant  and  gasoline  storage  should  be 
located  in  a  separate  building  and  at  a  reasonable  distance  from  the 
main  building,  in  order  to  minimize  danger  from  fire. 


Condensed  Milk  and  Milk  Powder  8i 


PART  III 

MANUFACTURE  OF  UNSWEETENED  CONDENSED 
MILK 

EVAPORATED  MILK 

CHAPTER  VIII 
DEFINITION 

There  are  three  kinds  of  unsweetened  condensed  milk  on  the 
market,  namely,  evaporated  milk,  formerly  called  evaporated  cream, 
plain  condensed  bulk  milk  and  concentrated  milk. 

Evaporated  milk  is  cow's  milk  condensed  in  vacuo  at  the  ratio 
of  about  two  to  two  and  one-half  parts  of  fresh  milk  to  one  part 
of  condensed  milk.  It  is  of  the  consistency  of  thin  cream  and 
reaches  the  market  in  hermetically  sealed  cans  varying  in  size  from 
eight  ounces  to  one  gallon.  Evaporated  milk  is  preserved  by  ster- 
ilization in  steam  under  pressure.  When  properly  made,  it  will  keep 
indefinitely,  but  is  best  when  fresh. 

QUALITY  OF  FRESH  MILK 

In  the  manufacture  of  evaporated  milk  the  psysiological  nor- 
mality and  the  chemical  purity  and  sweetness  of  the  freshniilk  are 
factors  even  more  important  than  in  the  case  of  sweetened  con- 
densed milk.  A  uniformly  satisfactory  and  marketable  product  can- 
not be  manufactured,  unless  the  milk  is  normal  and  pure  in  every  re- 
spect. The  reason  for  this  largely  lies  in  the  fact,  that  defects  the 
fresh  milk  may  have,  are  greatly  magnified  and  intensified  by  the 
high  sterilizing  temperature  to  which  the  evaporated  milk  is  sub- 
jected. While,  from  the  biological  point  of  view,  contaminations  of 
this  milk  are  largely  rendered  harmless  by  sterilization,  defective 
fresh  milk  cannot  be  made  into  a  marketable  product,  because  such 
milk  does  not  survive  the  process. 

It  should  be  understood  that  any  condition  or  factor  that,  in  the 
slightest  degree,  increases  the  tendency  or  ability  of  the  casein  to 


82  Condensed  Milk  and  Milk  Powder 

curdle,  tends  toward  the  formation  of  a  hard,  unshakable  coagulum 
during  sterilization,  and  makes  the  manufacture  of  a  marketable 
product  difficult.  Albnormal  milk  of  this  type  may  come  from  cows 
approaching  parturition,  or  too  soon  after  calving,  or  milk  from 
cows  suffering  from  disease,  generalized  or  local,  or  from  cows  in 
poor  and  abnormal  physical  condition,  which  may  be  brought  about 
by  poor  care,  over  feeding,  feeding  the  wrong  kinds  of  feed,  or 
feed  in  poor  condition,  exposure  to  abnormally  hot  weather  and 
fiies,  or  any  other  condition  which  disturbs  the  physiological  func- 
tions of  the  animal  and  thereby  affects  the  physical,  chemical,  and 
physiological  properties  of  the  milk ;  or  it  may  be  due  to  improper 
care  of  the  milk,  causing  it  to  be  excessively  contaminated  with  germ 
life,  or  to  be  relatively  high  in  acid.  All  such  milk  renders  the 
quality  of  the  finished  product  uncertain  and  may  result  in  heavy 
loss. 

In  view  of  these  facts  it  is  obvious  that  the  greatest  care  should 
be  exercised  on  the  receiving  platform,  inspecting  every  can  of  milk, 
using  the  most  reliable  means,  as  recommended  in  Chapter  III  on 
"Control  of  Quality,"  p.  28,  to  detect  suspicious  milk,  and  reject- 
ing all  milk  that  fails  to  reach  the  sanitary  standard  adopted  by  the 
factory. 

HEATING  THE  MILK 

The  equipment  for  heating  the  milk  should  be  such  as  to  enable 
the  factory  to  heat  the  milk  with  the  least  possible  delay,  so  as  to 
avoid  the  development  of  acid.  In  the  manufacture  of  evaporated 
milk,  the  batches  of  condensed  milk  in  the  vacuum  pan  must  be  rel- 
atively small.  This  milk  foams  more  in  the  pan  than  the  heavier 
sweetened  condensed  milk.  Also,  it  is  not  condensed  to  as  high  a 
degree  of  concentration.  These  factors  reduce,  therefore,  the  ca- 
pacity of  the  pan.  If  the  milk  is  heated  in  the  hot  wells,  either  by 
steam  jackets  or  by  turning  steam  direct  into  the  milk,  it  is  advis- 
able to  use  numerous  small  wells,  rather  than  but  one  or  a  few 
large  ones.  These  small  wells  fill  rapidly  and  the  nfilk  can  be  heated 
without  delay.  This  system  makes  it  possible  to  render  the  bacteria 
inactive  and  harmless  practically  as  soon  as  the  milk  arrives,  min- 
imizing the  danger  of  acid  formation. 

Steam  may  be  saved  if  the  milk  is  forewarmed  by  running  it 
through  coils  inclosed  in  a  chamber  of  exhaust  steam,  but  the  coils 


Condensed  Milk  and  Milk  Powder  83 

increase  the  labor  and  difficulty  of  cleaning.  It  is  best  to  heat  the 
milk  to  as  near  the  boiling  point  as  possible  and  hold  it  there  for 
five  to  ten  minutes,  provided  that  the  capacity  of  the  factory  war- 
rants this  delay.  In  this  heating  the  casein  of  the  milk  is  somewhat 
changed.  There  occurs  partial,  though  invisible,  precipitation,  and 
the  higher  the  temperature  to  which  the  milk  is  heated,  the  more 
pronounced  is  this  change.  This  change  is  desirable,  because  the 
casein  thereby  surrenders,  to  a  limited  extent,  its  power  and  ten- 
dency to  form  a  firm  curd  in  the  sterilizer. 

CHAPTER    TX 
CONDENSING 

The  same  apparatus,  the  vacuum  pan  and  pump,  are  used  for 
condensing  the  milk,  and  the  process  of  condensing  is  principally 
the  same  as  in  the  case  of  sweetened  condensed  milk.  The  fresh 
milk  is  condensed  at  the  ratio  of  two  to  two  and  one-half  parts  of 
fresh  milk  to  one  part  of  condensed  milk.  In  some  factories  it  is 
customary  to  superheat  the  milk  in  the  pan  before  it  is  drawn  ofif, 
i.  e.,  the  steam  to  the  jacket  and  coils  is  shut  ofif,  the  water  valve  is 
closed,  the  vacuum  pump  is  stopped  and  "live"  steam  is  passed  into 
the  condensed  milk.  This  is  done  to  swell  or  thicken  the  milk  and 
partly  precipitate  the  curd,  in  order  to  prevent  the  formation  of  too 
hard  a  curd  in  subsequent  sterilization.  When  the  vacuum  has 
dropped  to  about  six  or  eight  inches  and  the  temperature  has  risen 
to  180  or  200  degrees  F.,  the  super-heating  is  stopped,  the  vacuum 
pump  is  started  again  and  the  condensing  completed.  In  other  fac- 
tories the  superheating  is  omitted. 

STRIKING 

The  striking,  or  sami)ling  and  testing  for  densitw  of  evaporated 
milk,  is  more  easily  accomplished  than  that  of  the  sweetened  con- 
densed milk.  When  this  product  has  nearly  reached  the  proper 
density,  it  is  not  viscous  and  syrupy,  containing  no  cane  sugar.  It 
resembles  in  consistency  rich  milk  or  thin  cream  and  has  a  specific 
gravity  of  1.05  to  1.075  ^^  ^S-S  degrees  C.  or  60  degrees  F. 

Samples  are  drawn  from  the  vacuum  pan  as  described  under 


84  Condensed  Milk  and  Milk  Powder 

sweetened  condensed  milk  and  the  density  can  be  readily  determ- 
ined by  means  of  a  hydrometer.  Beaume  hydrometers,  registering 
from  I  to  15  degrees  B.,  are  generally  used.  As  it  is  important  that 
the  determinations  be  accurate,  the  hydrometer  should  be  sensitive 
and  its  scale  should  be  subdivided  into  tenth  degrees.  The  batch 
should  be  "struck"  at  a  uniform  temperature,  say  120  degrees  F., 
so  as  to  avoid  misleading  readings  of  the  hydrometer.  A  difference 
of  a  few  tenths  degrees  Beaume  affects  the  behavior  of 
the  evaporated  milk  in  the  sterilizer  very  appreciably.  If  the 
density  is  too  great  the  product  may  badly  curdle  during  steriliza- 
tion. If  the  density  is  too  low  the  evaporated  milk  may  be  below 
the  legal  standard.  It  is  advisable  for  the  operator  to  use  a  pail  of 
water  of  the  proper  temperature,  when  he  strikes  the  batch,  so  that 
he  can  adjust  the  temperature  of  the  milk  in  the  hydrometer  jar 
readily  and  quickly,  and  need  not  depend  entirely  on  the  temperature 
of  the  milk  in  the  pan,  which  may  change  several  degrees  while  he  is 
engaged  in  the  operation  of  striking. 

While  the  Beaume  hydrometers  should  be  used  at  the  tem- 
perature for  which  they  are  graduated,  which  is  60  degrees  F., 
they  answer  all  practical  purposes  at  any  other  temperature;  at  120 
degrees  F.  for  instance.  The  chief  essential  is  to  take  the  reading 
at  some  uniform  and  definite  temperature  and  read  the  Beaume  at 
that  same  temperature  in  the  case  of  every  batch.  In  that  way  the 
results  are  comparable.  The  operator  soon  learns  that  at  a  given 
temperature  the  evaporated  milk  of  proper  density  shows  a  certain 
Beaume  reading.  When  the  reading  is  higher  or  lower,  the  milk 
has  either  been  condensed  too  much  or  not  enough. 

The  same  formula,  however,  cannot  be  used  under  all  condi- 
tions. No  rule-of-thumb  method  of  determining  the  density  can 
therefore  be  established.  Aside  from  the  degree  of  condensation, 
the  specific  gravity  of  the  milk  varies  with  locality,  season  of  year, 
quality  of  milk,  etc.  This  means  that  what  is  the  proper  Beaume 
reading  in  one  locality,  or  at  one  season  in  the  same  locality,  may  be 
entirely  wrong  in  another  locality  or  at  other  seasons  in  the  same 
locality.  If  uniformity  in  the  density  and  behavior  of  the  batches 
of  evaporated  milk  is  to  be  secured  throughout  the  year,  the  operator 
must  watch  the  behavior  of  his  milk  from  day  to  day  and  from 
season  to  season  and  he  must  modify  the  Beaume  reading  in  ac- 


Condensed  Milk  and  Milk  Powder 


85 


m 


KiK-  'A'i.  Beaume 
liyilrometer  for 
evaporated  milk 


Courtesy   of 

C.  J.  Tagliabue 

Mfg.  Co. 


cordance  with  the  changing  conditions.  This  is  one 
of  the  all  important  stages  of  manufacture,  where  re- 
lentless and  careful  study  and  watchfulness  are  indis- 
pensable. 

In  order  to  make  absolutely  sure  that  the  density 
of  the  evaporated  milk  is  right,  it  is  advisable  to  get  it 
just  as  near  right  as  possible  in  the  pan  and  then  draw 
the  milk  from  the  pan  into  a  standardizing  vat  large 
enough  to  accommodate  the  entire  batch.  The  operator 
then  tests  the  milk  again  and  this  second  estimation 
he  can  perform  more  carefully,  because  he  is  then  re- 
lieved of  the  responsibility  of  attendiag  to  the  opera- 
tioji  of  the  vacuum  pan.  If  the  evaporated  milk  hap- 
pens to  be  a  trifle  too  heavy  he  can  dilute  it  with  dis- 
tilled water  until  the  Beaume  reading  is  ju.st  right. 

Correction  of  Beaume  Reading  at  Temperatures 
Other  than  60  Degrees  F. — At  a  temperature  of  120 
degrees  F.  the  Beaume  reading  of  the  finished  batch 
of  standard  evaporated  milk  may  vary  between 
about  6  and  8  degrees  B.,  according  to  season  of  year 
and  locality.  At  60  degrees  F.  the  Beaume  reading  is 
approximately  1.88  degrees  B.  higher. 

If  it  is  desired  to  record  the  Beaume  reading  at 
the  correct  temperature,  i.  e.,  60  degrees  F.,  and  it  is 
not  convenient  to  cool  the  evaporated  milk  to  that  tem- 
perature, the  reading  at  any  temperature  may  be  cor- 
rected as  follows :  when  the  temperature  at  which  the 
Beaume  reading  is  taken  is  above  60  degrees  F.,  mul- 
tiply the  difiference  between  the  temperature  of  the 
observd  reading  and  60  by  the  factor  .0313  and  add  the 
product  to  the  observed  reading. 

Example:  Beaume  at  120  degrees  F.  is  6.8;  what 
is  the  reading  at  60  degrees  F.  ? 

Answer :    6.8  +  (60  x  .0313 )  =  8.68  degrees  B. 

The  corrected  Beaume  reading  is  8.68  degrees  B. 
When  the  temperature  at  which  the  reading  is  made 
is  below  60  degrees  F.,  multiply  the  difiference  be- 


86  Condensed  Milk  and  Milk  Powder 

tween  the  temperature  of  the  observed  reading  and  60  by  the  fac- 
tor  .0313   and    subtract   the   product    from   the   observed    reading. 

Calculation  of  Specific  Gravity  from  Beaume  Reading. — In 

order  to  record  the  density  of  the  evaporated  milk  in  terms  of  spe- 
cific gravity,  instead  of  Beaume  degrees,  the  following  formula  may 
be  used : 

145.5 
Specific  gravity  ^ ^^^ p-;   B   ^   Beaume  reading  at  60 

degrees  F. 

Example:     Beaume  reading  at  60  degrees  F.  is  8  degrees  B. 
What  is  the  specific  gravity? 

Specific  gravitv  =:r =  1.0582 

145.5—8 


CHAPTER  X 
HOMOGENIZING 

Purpose. — The  introduction  of  the  homogenizer  in  milk  con- 
densing factories  is  a  comparatively  recent  innovation.  The  object 
of  its  use  is  to  avoid  the  separation  of  the  butter  fat  in  the  evaporated 
milk  after  manufacture. 

The  butter  fat  is  present  in  milk  in  the  form  of  minute  globules. 
These  fat  globules  are  lighter  than  the  rest  of  the  ingredients  of  the 
milk.  They,  therefore,  show  a  strong  tendency  to  rise  to  the  sur- 
face and  to  form  a  layer  of  thick  cream  in  the  cans.  \Vhen  these 
cans  are  subsequently  subjected  to  agitation,  as  is  the  case  in  trans- 
portation, this  cream  churns,  forming  lumps  of  butter.  This  ten- 
dency of  evaporated  milk  to  separate  in  storage  and  churn  in  trans- 
portation is  especially  noticeable  with  milk  rich  in  fat  and  in  which 
the  large  fat  globules  predominate.  In  Jersey  and  Guernsey  locali- 
ties, it  is  more  difficult,  therefore,  to  manufacture  evaporated  milk 
that  does  not  separate,  than  in  Holstein  and  Ayrshire  localities.  While 
separated  and  churned  evaporated  milk  is  perfectly  sound  and  in 
every  way  as  valuable  as  a  food,  as  it  would  be  without  this  separa- 
tion, it  does  not  sell  in  this  condition.     It  is  rejected  on  the  market. 

This  tendency  toward  fat  separation  can  be  minimized  and  fre- 
quently entirely  prevented  by  increasing  the  viscosity  of  the  evapo- 


Condensed  Milk  and  Milk  Powder 


87 


rated  milk.  This  can  be  accomplished  by  superheating  the  milk  in 
the  pan  and  by  prolonging  the  sterilizing  process,  raising  the  heat 
very  slowly.  However,  there  are  conditions  when  even  this  pre- 
caution does  not  permanently  avoid  separation  of  the  fat.  In  such 
cases,  the  proper  use  of  the  homogenizer  furnishes  a  reliable  means 
to  guard  against  this  difficulty. 

Principle  of  the  Homogenizer. — The  principle  of  the  homogen- 
izer is  to  force  the  milk  under  high  pressure  through  exceedingly 
small,  microscopic  openings.  By  so  doing  the  fat  globules  are  broken 
up  so  finely  that  they  fail  to  respond  to  the  gravity  force,  they  can- 
not rise  to  the  surface  and  therefore  remain  in  homogeneous  emul- 
sion. The  value  of  the  homogenizer  lies  in  removing  the  funda- 
mental cause  of  this  separation.  It  reduces  the  fat  globules  to  such 
small  size  that  their  buoyancy,  or  gravity  force,  is  not  great  enough 
to  overcome  the  resistance  of  the  surrounding  liquid. 

Kinds  of  Homogenizers. — There  are  at  this  time  two  makes  of 
homogenizers  in  use  in  this  country,  namely,  the  "Gaulin"  and  the 


"Progrt 


homogenizer. 


In  the  Gaulin  homogenizer, 
the  milk  is  forced,  by  means  of 
single-acting  ]>unips,  against  an 
agate  valve  which  presses  against 
a  ground  valve  seat.  The  milk 
has  to  pass  between  the  ground 
surfaces  of  this  valve  and  valve 
seat.  This  causes  the  fat  glob- 
ules to  be  divided  very  minutely. 
Tliis  type  of  homogenizer  has 
not  been  used  much  as  yet  in  the 
manufacture  of  evaporated  milk 
and  but  little  is  known  concern- 
ing its  effect  on  this  product. 
In  the  Progress  homogenizer  the  homogenizing  j^rinciple  con- 
sists of  forcing  the  milk,  by  means  of  single  acting  pumps,  between 
a  series  of  discs  with  ground  surfaces.  The  discs  lay  flat  one  upon 
the  other,  they  are  enclosed  in  a  cylinder  and  are  held  in  place  by  a 
rod  running  through  their  center.  The  discs  are  pressed  against 
each  other  by  a  heavy  spiral  screw%  which  regulates  the  ]>ressure  to 


I  hi-    i'romt'NS   homoKenizer 

Cniirt.-fy   of 
Dairy   .Machinery  &   Construction   Co. 


88  Condensed  Milk  and  Milk  Powder 

which  the  milk  is  subjected.  The  milk  passes  from  the  center  to  the 
periphery  of  the  discs.  While  being  forced  through  the  discs  the 
fat  globules  are  split  up  very  finely.  The  discs  used  in  this  machine 
are  of  two  types.  One  type  has  very  fine  irregular  grooves.  The 
milk  shoots  through  these  grooves  against  hard  shoulders.  Tlie 
other  type  of  discs  has  smooth  surfaces  but  their  area  of  contact  is 
narrow.  The  milk  passes  through  between  these  smooth  surfaces. 
The  Progress  homogenizer  is  used  in  numerous  evaporated  milk 
factories  in  this  country  and,  where  operated  properly,  it  overcomes 
fat  separation  very  satisfactorily,  without  damaging  the  other  in- 
gredients of  milk. 

Operation  of  the  Homogenizer. — In  order  to  avoid  fat  separa- 
tion it  is  necessary  to  reduce  the  fat  globules  to  about  one-third  their 
original  size.  If  enough,  pressure  is  applied  to  divide  the  fat  glob- 
ules much  smaller,  there  is  a  tendency  to  also  change  the  properties 
of  the  casein,  causing  it  to  give  rise  to  copious  precipitation,  when 
the  evaporated  milk  is  sterilized,  and  making  the  finished  product 
curdy  and  unmarketable.  In  this  case  the  cure  would  be  more  disas- 
trous than  the  original  defect.  Great  care  must,  therefore,  be  exer- 
cised, guarding  against  the  use  of  excessive  pressure  that  would  in- 
jure the  casein.  Experiments  have  shown  that  a  pressure  of  be- 
tween seven  hundred  and  one  thousand  pounds  per  square  inch  is 
sufficient  to  prevent  fat  separation  and  is  practically  harmless  as 
far  as  its  efifect  on  the  casein  in  the  evaporated  milk  is  concerned. 

The  evaporated  milk  is  run  through  the  homogenizer  hot,  just 
as  it  comes  from  the  vacuum  pan  or  standardizing  tank.  The  first 
pailful  of  milk  passing  through  the  machine  should  be  returned  to 
the  supply  tank,  as  on  the  start,  the  pressure  is  not  uniform  and 
homogenization  is  incomplete. 

The  pistons,  cylinders,  valves  and  pipes  of  the  homogenizer 
should  be  kept  in  sanitary  condition.  They  are  difficult  to  clean. 
After  homogenizing,  the  machine  should  be  kept  in  operation,  run- 
ning water  through  it,  until  most  of  the  remnants  of  evaporated 
milk  are  rinsed  out ;  then  hot  water  containing  some  active  alkali 
should  be  ptmiped  through ;  this  should  be  followed  by  clean  hot 
water  and  steam.  Unless  this  machine  is  kept  scrupulously  clean, 
it  may  become  a  dangerous  source  of  contamination,  infecting  the 
evaporated  milk  with  spore  forms  that  are  exceedingly  resistant  and 


Condensed  Milk  and  Milk  Powder 


89 


which  are  hable  to  pass  into  the  finished  product  alive,  in  spite  of 
the  steriHzing  process,  causing  the  goods  to  be  a  complete  loss,  due 
to  subsequent   fermentation. 

CHAPTER  XI 


COOLING 

In  the  cooling  of  the  evaporated  milk,  no  attention  need  be  paid 
to  sugar  crystallization.  In  this  class  of  goods  there  is  plenty  of 
water  to  keep  the  milk  sugar  in  ready  solution.  The  evaporated  milk 
can,  therefore,  be  cooled  as  rapidly  as  facilities  permit.  The  cooling 
may  be  accompHsiied  in  similar  ways  as  are  used  for  cooling  fresh 
milk.  From  the  homogenizer  the  evaporated  milk  is  run  over  a  sur- 
face cooler,  or  cooling  coil.     It  is  advisable  to  cover  the  coils  with 

a  jacket  of  galvanized  iron,  tin  or 
copper,  so  as  to  avoid  undue  con- 
tamination of  the  milk  from  dust, 
tiies,  and  other  undesirable  agents. 
In  some  condenseries,  the  hot  evap- 
orated milk  is  forced  through  dou- 
ble pipes,  cold  water  passing  be- 
tween the  inner  and  outer  pipe,  or 
the  coils  through  which  the  milk 
passes  are  submerged  in  a  tank  of 
cold  water.  The  only  objection  to 
this  system  is  that  the  pipes  are  more  difficult  to  clean  than  in  the 
case  of  an  open  surface  cooler.  Where  this  system  is  used,  the  pipes 
should  be  equipped  with  sanitary  fittings  so  that  they  can  be  readily 
swabbed  out  from  both  ends.  In  other  factories,  the  same  cooling 
equipment  is  used  as  for  sweetened  condensed  milk,  with  the  excep- 
tion that  cold  water  is  run  into  the  cooling  tank  at  once.  If  the 
evaporated  milk  is  not  homogenized  it  should  be  cooled  as  soon  as  it 
leaves  the  vacuum  pan. 

The  evaporated  milk  should  be  cooled  to  as  low  a  temperature 
as  the  available  water  permits.  If  the  condensery  is  not  in  position 
to  fill  the  avaporated  milk  into  tin  cans  immediately  after  cooling,  it 
is  advisable  to  place  the  covers  on  the  40-quart  cans  and  submerge 
them  in  cold  or  ice  water.     Condenseries  which  are  provided  with 


rig.  34. 

Surface  cooler  for  evaporated  milk 

Courtesy  of  Arthur  Harris  &  Co. 


90 


CoNDKNSKD  AIlLK  AND  MiLK   PoWDRR 


artificial  refrigeration  may  store  the  evaporated  milk,,  before  filling, 
in  glass-lined  storage  tanks  cooled  with  brine.  This  practice  makes 
it  possible  to  mix  all  the  batches  of  one  day's  make  together  and 

thereby  increase  the  uniform- 
ity of  the  product.  At  this 
stage  of  the  process  the  evapo- 
rated milk  is  not  sterile,  nor 
does  it  contain  any  preserva- 
tive, such  as  sucrose ;  it  is  not 
concentrated  enough  to  be 
preserved  by  the  absence  of 
moisture.  If  exposed  to  warm 
temperatures  for  any  length 
of  time,  therefore,  its  acidity 
will  increase,  thereby  render- 
ing the  subsequent  sterilizing 
process  difficult. 


Fig.  35.     Hand  flUinK  machine  for 
evai)orated  milk 

Courtesy  of  Arthur  Harris  &  Co. 


FILLING 

The  cooled,  evaporated  milk  is  filled  into  tin  cans  ranging  in  size 
from  eight  ounces  to  one  gallon.  The  gallon  cans  are  usually  filled 
by  hand.  The  filling  of  the  smaller  cans  is  done  by  automatic  filling 
machines. 

Of  late  years  much  ])rog- 
ress  has  been  made  in  the 
construction  of  diiTerent  types 
of  filling  machines  for  evapo- 
rated milk.  The  openings  in 
the  cans  through  which  the 
cans  are  filled  range  from  the 
Sanitary  can,  which  is  filled 
with  the  top  of  the  can  en- 
tirely removed,  to  the  vent- 
hole  can  with  an  opening  of 
not  more  than  one-eighth  inch 
in  diameter.  The  filling  ma- 
chines are  constructed  to  fill 

,  ,  Fig.   36.     Elgin   filling  machine  for 

by  gravity,  under  pressure,  or  evaporated  miik 

'it,  ,ro^1lr^  Courtesy   of   The  Sprague   Canning 

in  vacuo.  Machinery  Co. 


Condensed  Milk  and  Milk  Powder 


91 


These  filling  machines  should  be  thoroughly  washed  and  freed 
from  all  remnants  of  evaporated  milk  adhering  to  the  valves  and 
other  parts  after  each  use.    Remnants  of  milk  left  in  any  part  of  the 


Vent  hole  cans 


Fig.   38 


Fig.    Hi).      Tlie    vacuum   filler 

Courtesy  of  The   Sprague   Canning   Machinery   Co. 


filling  machine  decompose  readily  and  impair  the  wholesomeness  and 
marketable  properties  of  the  product.     This  is  an  important  point 


.92 


Condensed  Milk  and  Milk  Powder 


and  one  too  often  neglected.  Much  of  the 
spoiled  evaporated  milk  may  be  the  result 
of  the  use  of  unsanitary  and  unclean  filling 
machines.  The  fact,  that  the  evaporated 
milk  is  sterilized  after  it  leaves  the  filling 
machine,  is  no  excuse  for  unclean  filling  ma- 
chines. The  operator  should  bear  in  mind 
that  the  milk  running  through  an  unclean 
filling  machine  becomes  contaminated  with 
millions  of  bacteria.  The  more  bacteria  it 
contains,  the  more  difficult  it  is  to  render  it 
perfectly  sterile.  Furthermore,  spore- 
forms  are  prone  to  develop  in  the  decaying 
remnants  of  milk ;  these  spores  are  very  re- 
sistant and  require  excessively  high  steriliz- 
Fig.  40.  The  Sprague-Coibert  ing  tcmpcraturcs  to  be  destroyed. 

rotary  tipping  macliine 

Courtesy  of   The  Sprague 
Canning  Machinery  Co. 

SEALING 

The  filled  cans  should  be  capped  and  sealed  at  once.  The  seal 
must  be  hermetical  and  strong  enough  to  withstand  the  strain  of  the 
subsequent  sterilizing  process.  With  the  exception  of  the  "Sanitary 
can."  seals  without  solder  have  so  far  proven  unsatisfactory  in  the 
canning  of  evaporated  milk.  They  are  prone  to  weaken  in  the  ster- 
ilizer and  cause  "leakers."  Most  of  the  cans  on  the  market  contain- 
ing evaporated  milk  are,  therefore,  sealed  with  solder.  Sealing  evap- 
orated milk  cans  with  solder  is  by  far  the  safest  method.  The  sani- 
tary can,  however,  has  been  found  to  furnish  a  satisfactory  seal  with- 
out solder.    For  details  of  methods  of  sealing  see  Chai>ter  VII. 


Condensed  Milk  and  Milk  Powder  93 

CHAPTER  XII 

STERILIZING 

The  sealed  cans  are  now  ready  for  the  sterilizer.  If  they  cannot 
be  sterilized  within  an  hour  or  two  they  should  be  submerged  in  ice 
water  or  placed  in  a  refrigerating  room  until  the  sterilizer  is  ready 
for  them.    This  precaution  is  especially  advisable  in  summer. 

Purpose  of  Sterilization. — The  chief  purpose  of  subjecting  the 
evaporated  milk  to  the  sterilizing  process  is  to  kill  all  germ  life  and, 
therefore,  preserve  the  product  permanently.  When  the  hermetically 
sealed  cans  come  from  the  sealing  room,  their  contents  are  not  sterile. 
The  only  means  to  preserve  this  milk  is  to  subject  it  to  temperatures 
high  enough  to  kill  all  forms  of  ferments,  organized  and  unorganized, 
vegetative  cells  and  spores.  The  success  of  the  manufacture  of  this 
product  depends  to  a  large  extent  on  the  process  of  sterilization. 

Aside  from  this,  the  manufacturer  aims  to  gain  another  com- 
mercially important  condition,  namely,  to  prevent  the  separation  of 
the  butter  fat.  Before  sterilization,  there  is  nothing  to  prevent  the 
fat  from  separating  out  in  the  evaporated-  milk  and  from  churning 
in  transportation,  unless  the  evaporated  milk  was  homogenized.  This 
is  a  highly  undesiraWe  characteristic,  making  the  goods  unmarket- 
able. The  sterilizing  process  helps  to  so  change  the  physical  proper- 
ties of  the  milk,  that  this  tendency  of  the  fat  to  separate  is  greatly 
minimized.  The  sterilizing  temperatures  used,  further  lend  to  the 
evaporated  milk  a  creamy  consistency  and  yellowish  color,  giving 
the  product  a  sennblance  of  richness. 

Sterilizers. — The  apparatus  used  for  sterilizing  is  a  huge  boiler- 
like, hollow,  iron  cylinder  or  box.  It  opens  either  at  one  end  or  on 
the  side.  Its  interior  is  equipped 
with  a  revolving  framework, 
steam  inlet  and  exhaust,  a  water 
distributing  pipe  running  the  en- 
tire length  of  the  sterilizer,  and 
a  water  exhaust.  The  sterilizer 
carries  on  its  exterior  a  steam 
gauge,  a  vacuum  gauge,  a  water 

,  ,  ^^  ,  ,  Fig.  41.     Sterilizer  for  evaporated  milk 

gauge,  a  blow-off   valve    and    a         ^^^^^^^^  „,  ^^^^^^  ^^^^.^  ^  ^„_ 


94 


Condensed  Milk  and  Milk  Powder 


high-temperature  thermometer  (registering  to  about  280  degrees  F.). 
In  some  makes  of  sterihzers  the  interior  frame-work  does  not 
revolve  on  its  axis,  but  moves  back  and  forth  by  means  of  a 
direct-acting,  steam-driven  piston,  attached  to  the  back  end  of 
the  steriHzer.  The  purpose  of  keeping  the  cans  in  motion  while 
heat  is  applied,  is  to  heat  the  contents  rapidly  and  uniformly,  and  to 
prevent  the  evaporated  milk  from  baking  onto  the  sides  of  the  cans. 

Loading  the  Sterilizer. — The  sealed  tin  cans  are  placed  in  heavy 
iron  tra\  s.  usualh  holding  twenty-four  i6-ounce  cans  or  six  i-gallon 
cans.  The  loaded  trays  are  slid  and  locked  into  the  framework  in 
the  interior  of  the  sterilizer.  The  sterilizer  is  closed  with  heavy 
iron  doors  and  the  framework  is  put  in  motion.  In  some  makes  of 
sterilizers  the  interior  consists  of  a  large  perforated  iron  box  re- 
volving on  its  axis.  In  this  case  the  cans  are  simply  piled  into  this 
box,  no  trays  being  used. 

Uniform  Distribution  of  Heat. — Where  no  water  is  used  in  the 
sterilizer  during  the  sterdHzing  process,  it  is  important  that  there  be 
a  free  air  space  between  every  two  layers  of  cans,  so  as  to  allow  the 

s  t  e  a  m     to    circulate 

freely  and  to  come  in 

direct     contact     with 

every  can.    When  the 

cans  are  piled  into  the 

sterilizer  six  to  twelve 

layers    deep    without 

any  free  air  space  be- 
tween layers,  the  cans 

in   the   center   do  not 

receive  as  much  heat 

as  those  at  the  sides, 

ends,  top  and  bottom. 

This  causes  irregular 

heating  and  imperfect 

sterilization. 

A  satisfactory  means  of  insuring  even  distribution  of  heat  is  to 
fill  the  sterilizer  about  one-third  full  of  water,  so  that,  when  the  ster- 
ilizer is  in  operation,  the  cans  pass  through  this  water,  with  each 
revolution  of  the  frame  work.    Water  distributes  the  heat  uniformly. 


Fig.  43.     Time  control   gauKe 

Courtesy  of 
C.  J.   Tagliabue  Mfg.  Co. 


Condensed  Milk  and  Milk  Powder 


95 


rapidly  and  there  is  no  danger  of  the  formation  of  air  ])ockets  be- 
tween the  cans.  Since  the  heat  is  appHed  by  steam  under  pressure 
the  temperature  of  the  water  is  equal  to  that  of  the  steam  in  the 
sterilizer.  This  precaution  is  especially  necessary  in  the  case  of 
baby-size  cans  (eight  ounces  )  which  are  usually  piled  in  stacks  more 
than  two  deei).  When  sterilizing  in  the  absence  of  water  there  is 
danger  of  lack  of  uniformity  of  the  amount  of  heat  they  receive. 

Temperature  and  Time  of  Exposure. — When  the  sterilizer  is 
filled  with  the  cans  and  closed,  the  frame  work  is  set  in  motion  and 
steam  is  turned  into  the  sterilizer.  In  order  to  hasten  the  heating 
and  expel  all  the  air,  the  exhaust  and  safety  should  be  left  open 
until  the  temperature  has  risen  to  212  degrees  F.  This  temperature 
is  usually  reached  in  about  ten  to  fifteen  minutes.  The  exhaust  and 
safety  are  then  closed. 

From  this  point  on,  the  process  must  depend  on  locality,  sea.son 
of  year  and  condition,  properties  and  concentration  of  the  milk.  No 
formula  can  be  laid  down  which  can  be  depended  on  to  give  uniformly 

satisfactory  results  under 
all  conditions.  The  tem- 
perature should  be  high 
enough  and  the  duration  of 
expo.sure  long  enough  to 
insure  absolute  sterility  of 
the  product  and  to  give  the 
milk  sufiicient  body  to  pre- 
vent the  separation  of  the 
butter  fat  in  subsequent 
storage.  The  temperature 
should  not  be  so  high  nor 
the  duration  of  exposure 
so  long,  as  to  cause  the 
formation  of  a  hard,  unshakable  curd  and  dark  color. 

Some  processors  use  a  very  short  process  with  high  tempera- 
tures, others  raise  the  heat  gradually  aud  not  to  quite  so  high  a 
degree.  The  more  gradual  heating  is  preferable,  as  it  gives  the 
product  a  better  body  and  more  viscosity,  which  is  necessary  to  keep 
the  fat  from  separating  in  storage.  The  author's  judgment  in  this 
matter  is,  that  it  is  not  safe  to  raise  the  temperature  to  less  than  230 


Tig.  44.     Temperature  control  grauge 

Courtesy   of  C.   ,J.   Tagliabue    Mfg.   Co. 


96  Condensed  Milk  and  Milk  Powder 

degrees  F.  and  it  is  advisable  to  heat  the  milk  to  234  to  236  degrees 
F.,  provided  that  the  milk  is  in  condition  to  stand  this  heat  without 
the  formation  of  too  firm  a  curd.  Where  the  maximum  tempera- 
ture to  which  the  milk  is  raised  in  the  sterilizer  is  230  degrees  F.  or 
thereabout,  the  raise  of  the  last  ten  degrees  should  occupy  from  thirty- 
five  to  forty-five  minutes,  and  this  time  should  be  about  evenly  dis- 
triibirted  over  the  ten  degrees. 

Qualifications  of  the  Processer. — The  operator,  or  the  person 
directing  the  sterilizing  process,  should  thoroughly  appreciate  the 
comiplexity  of  the  product,  understand  the  cause  and  effect  of  the 
many  influencing  factors,  study  the  cA^er-changing  conditions  and 
modify  the  process  in  accordance  with  prevailing  conditions.  He 
should  know  that  during  the  exceedingly  hot  summer  days,  when 
the  cows  suffer  from  heat  and  are  pestered  with  flies,  the  milk  will 
not  stand  as  much  heat  without  badly  curdling  in  the  sterilizer  as 
under  more  favorable  conditions.  He  should  know  that  toward  and 
during  the  fall  months  the  organisms  normally  present  in  milk  are 
more  resistant  and  require  higher  heat  to  be  destroyed,  than  earlier 
in  the  season. 

Rapid  and  Uniform  Cooling. — As  soon  as  the  required  heat 
has  been  given  the  milk  in  the  sterilizer,  the  steam  should  be  turned 
off  and  the  exhaust  and  drain  should  be  opened.  When  the  tempera- 
ture has  dropped  to  about  220  degrees  F.,  cold  water  should  be  turned 
into  the  sterilizer  while  the  cans  are  constantly  in  motion,  until  the 
cans  are  cool  enough  to  handle.  There  should  be  enough  cold  water 
available  to  reduce  the  temperature  to  70  or  80  degrees  F.  in 
twenty  minutes  for  gallons  and  in  ten  to  fifteen  minutes  for  small 
size  cans.  The  water  pipe  should  be  so  arranged  as  to  distribute 
the  water  uniformly  over  the  entire  length  of  the  sterilizer. 

If  the  process  is  to  be  successful,  the  processor  must  have  as 
nearly  perfect  control  of  the  heat  as  possible.  This  means  espe- 
cially, that  there  must  be  plenty  of  water  available  to  insure  rapid 
coo'ling  and  the  water  must  be  distributed  over  the  cans  uniformly. 
Insufficient  water  supply  and'  uneven  distri/bution  of  the  water  in 
the  sterilizer,  means  that  some  of  the  cans  are  exposed  to  the  steril- 
izing heat  longer  than  others,  causing  lack  of  uniformity  in  the 
smoothness  and  color  of  the  milk  of  different  cans  of  the  same 
batch.     Delavcd  cooling  owing  to  insufficient  water  supply  has  the 


Condensed  Milk  and  Milk  Powder  97 

further  disadvantage  of  causing  the  cans  to  bulge  badly,  owing  to 
the  difference  in  pressure  between  the  interior  and  exterior  of  the 
cans.  This  is  especially  noticeable  in  gallon-size  cans,  the  ends  of 
which  may  become  badly  distorted,  present  an  unsightly  appearance 
and  their  seams  and  seals  may  be  weakened  to  the  extent  of  pro- 
ducing "leakers." 

Fractional  Sterilization. — In  some  factories  fractional  steril- 
ization is  occasionally  practiced.  The  milk  is  heated  in  the  sterilizer 
to  considerably  lower  temperatures  than  those  stated  above,  and 
this  heating  is  repeated  on  two  or  three  successive  days.  The  prin- 
ciple of  this  process  is  to  kill  all  vegetative  forms  of  bacteria  dur- 
ing the  first  heating.  This  gives  the  spores  a  chance  to  develop 
into  vegetative  forms  by  the  second  and  third  days,  which  forms 
are  then  destroyed  during  subsec]uent  heating.  This  system  of 
sterilization  is  not  practical  for  general  use.  It  is  too  great  a  tax  on 
the  capacity  of  the  average  factory  and  increases  the  cost  of  manu- 
facture. It  should,  therefore,  be  made  use  of  only  in  exceptional 
cases,  when  it  is  known  that  a  certain  batch  of  milk  could  not  be 
put  through  the  higher  sterilizing  temperatures  without  causing  the 
product  to  become  permanently  curdy. 

SHAKING 

Purpose. — The  purpose  of  shaking  the  evaporated  milk  is  to 
mechanically  break  down  the  curd  that  may  have  been  formed  in 
the  process  of  sterilization  and  to  give  the  contents  of  the  cans  a 
smooth  and  homogeneous  body. 

The  high  temperatures  to  which  the  evaporated  milk  is  sub- 
jected in  the  sterilizer  have  a  tendency  to  coagulate  the  casein.  In 
the  case  of  normal,  fresh  milk  the  casein  coagulates  at  a  temperature 
of  269  degrees  F.  In  the  evaporated  milk,  made  from  perfectly  nor- 
mal and  sweet,  fresh  milk  the  casein  curdles  at  much  lower  tempera- 
tures, and  the  higher  the  ratio  of  concentration,  the  lower  the  tem- 
perature required  to  precipitate  the  casein.  It  seems  that  the  con- 
centration of  the  milk  intensifies  the  properties  of  milk  to  coagu- 
late when  subjected  to  heat.  This  factor  is  probably  largely,  though 
not  necessarily,  wholly  due  to  the  increase  of  the  per  cent,  of  lactic 
acid  in  the  evaporated  milk,  due  to  the  concentration.  If  the  fresh 
milk  contains  .17  per  cent,  lactic  acid,  a  concentration  of  two  and 


98 


Condensed  Milk  and  Milk  Powder 


one-fourth  parts  of  fresh  milk  to  one  part  of  evaporated  milk 
causes  the  evaporated  milk  to  contain  .17  x  2.25  =  .38  per  cent,  lac- 
tic acid.  With  this  amount  of  acid  acting  on  the  casein,  it  is  not 
difficult  to  understand  why  a  coagulum  is  often  fonned  in  the  ster- 
ilizer. While  the  formation  of 
this  coagulum  may  be  partly 
avoided,  under  certain  conditions 
it  appears  in  every  factory  and 
there  are  more  batches,  espe- 
cially in  summer,  that  come  from 
the  sterilizer  coagulated  than 
otherwise. 

In  this  condition  the  product 
is  not  marketable.  Some  means  must  be  provided,  therefore,  to  break 
up  this  curd  and  reduce  the  contents  of  the  cans  to  a  smooth,  homo- 
geneous and  creamy  body.  For  this  purpose  a  mechanical  shaker 
is  used. 


Figr.  45.     (Shaker 

Courtesy  of  Arthur  Harris  &  Co. 


Method  of  Shaking. — The  shaker  consists  of  one  or  more  heavy 
iron  boxes  or  boxes  made  of  black  iron  pipes.  These  boxes  are 
attached  to  an  eccentric.    The  trays  filled  with  evaporated  milk  cans 


Fig.  4(>.     Shaker 

Courtesy  of  The  Schaefer  Mfg.   Co. 


are  firmly  wedged  into  the  shaker.  When  the  shaker  is  in  operation, 
the  cans  are  shaken  back  and  forth  violently,  causing  the  curd  in 
the  cans  to  be  broken  up. 

Speed  of  the  Shaker. — If  the  shaker  is  to  perform  its  work 
properly,  it  must  have  long  enough  a  stroke  and  run  fast  enough  to 


Condensed  Milk  and  Milk  Powder  99 

cause  most  vigorous  agitation.  The  stroke  should  be  not  less  than 
two  and  one-half  inches  and  the  eccentric  should  revolve  not  less 
than  three  hundred  to  four  hundred  times  per  minute.  In  order  to 
acconiiplish  this  without  wrecking  the  machine,  the  shaker  must  be 
fastened  securely  to  a  solid  foundation. 

From  one-fourth  to  two  minutes'  shaking  is  usually  sufficient 
to  completely  break  down  a  soft  curd.  When  shaking  for  five  min- 
utes does  not  produce  a  smooth  milk,  the  product  is  usually  hope- 
lessly curdy  and  no  amount  of  additional  shaking  will  remedy  the 
defect. 

In  some  cases  it  has  been  possible,  however,  to  improve  the 
curdy  product  by  shaking  again  after  a  day  or  two.  Under  certain 
conditions,  age  seems  to  have  a  slight  mellowing  efifect  on  the  curd. 

Efficiency  of  Different  Typ^s  of  Shakers. — Some  shakers  have 
a  straight,  horizontal,  back  and  forth  motion.  Others  have  a  rotary 
or  elliptical  motion ;  the  latter  are  not  considered  as  effective  in  their 
work  as  the  former.  Some  of  the  sterilizers  in  which  the  interior 
frame  holding  the  cans,  moves  back  and  forth,  are  advertised  to 
shake  the  milk  as  well  as  sterilize  it.  Experience  has  .shown,  how- 
ever, that  the  shaking  performed  by  these  sterilizer-shakers  is  not 
sufficient  and  that  the  use  of  a  separate  shaker  is  necessary. 

Formation  of  Curd  not  Desirable  nor  Necessary. — It  should 
be  understood  that  the  processor  should  aim  to  get  only  a  very  slight 
and  soft  curd  in  his  product,  that  can  be  shaken  out  in  the  shaker 
in  one-fourth  to  one-half  minute.  When  the  curd  produced  is  firm, 
even  prolonged  shaking  will  not  prevent  the  appearance  in  the  fin- 
ished product  of  specks  and  small  lumps  of  curd.  Such  milk  is 
rejected  on  the  market. 

The  formation  of  curd  during  the  sterilizing  process  is  not  de- 
sirable and  is  not  necessary  as  far  as  the  marketable  properties  of 
the  evaporated  milk  is  concerned.  It  is  unavoidable,  however,  under 
many  conditions  and  as  long  as  it  can  be  confined  to  a  soft  curd  that 
readily  shakes  out.  no  harm  is  done. 

INCUBATING 

From  the  shaker,  the  cans  are  transferred  to  the  incubating  room. 
This  is  a  room  with  a  temperature  of  70  degrees  to  90  degrees  F. 
The  evaporated  milk  remains  there  ten  to  thirty  days.     The  pur- 


loo  Condensed  Milk  and  Milk  Powder 

pose  of  incivbation  is  to  detect  defective  milk  and  defective  cans 
before  they  leave  the  factory.  If  the  contents  of  any  of  the  cans 
have  not  been  completely  sterilized,  or  if  any  cans  have  the  minutest 
leak,  the  evaporated  milk  therein  will  spoil  within  the  time  of  incu- 
bation. Such  milk  either  sours,  curdles  or  becomes  solid,  or  it 
undergoes  gaseous  fermentation,  causing  the  appearance  of  "swell 
heads."  The  more  nearly  perfect  the  process  of  sterilization  and 
the  better  the  construction  and  seal  of  the  cans,  the  fewer  are  the 
spoiled  cans.  This  incubation  process  is  strictly  a  preventative  meas- 
ure. It  is  omitted  in  many  factories  where  the  cans  are  labeled, 
packed  and  shipped  to  their  destination  at  once,  or  put  in  ordinary 
storage  in  the  factory. 


CHAPTER    XIII 
PLAIN  CONDENSED  BULK  MILK 

Definition. — This  is  an  unsweetened  condensed  milk  made  from 
whole  milk,  or  partly,  Qr  wholly  skimmed  milk,  condensed  in  vacuo 
at  the  ratio  of  about  three  or  four  parts  of  fluid  milk  to  one  part  of 
condensed  milk.  It  is  usually  superheated  to  swell  and  thicken  it, 
and  it  has  the  consistency  of  rich  cream.  It  is  sold  in  lo-gallon 
milk  cans  to  ice  cream  factories  and  in  milk  bottles  to  the  direct 
consumer.  Plain  condensed  bulk  milk  is  not  sterile,  nor  is  it  pre- 
served by  sucrose.  Its  keeping  quality  is  similar  to  that  of  a  high 
cjuality  pasteurized  milk. 

Quality  of  Fresh  Milk. — The  sweeter  and  purer  the  fresh  milk 
or  skim  milk,  the  better  will  be  the  quality  of  this  product.  Old  milk, 
or  skim  milk  in  which  the  acid  development  has  made  considerable 
headway,  tends  to  form  a  lumpy,  plain  condensed  bulk  milk.  How- 
ever, since  this  milk  is  not  subjected  to  sterilizing  temperatures  and 
is  used  up  quickly  after  manufacture,  the  quality  of  the  fresh  milk 
from  which  it  is  made,  is  not  of  such  magnitude  as  in  the  case  of 
evaporated  milk. 

Heating. — In  the  manufacture  of  plain  condensed  bulk  milk  the 
heating  is  accomplished  much  in  the  same  manner  as  in  the  case  of 
sweetened  condensed  milk  and  evaporated  milk.  The  milk  is  usually 
heated  bv  turning  steam  direct  into  it. 


Condensed  Milk  and  Milk  Powder  ioi 

It  is  advisable,  however,  to  heat  this  milk  only  to  a;bout  150  to 
160  degrees  F.  in  order  to  secure  a  nice  "liver"  (coagulum),  when 
it  is  superheated  in  the  pan.  If  the  milk  is  heated  to  the  boiling 
point  in  the  forewarmers,  it  does  not  respond  to  the  superheating  in 
the  pan  as  satisfactorily. 

Condensing. — The  condensing  of  plain  condensed  bulk  milk  is 
done  in  the  vacuum  in  a  similar  manner  as  described  under  evapo- 
rated milk,  except  that  the  evaporation  is  carried  farther. 

Superheating. — When  the  x:ondensation  is  nearly  completed  the 
milk  in  the  pan  is  superheated.  This  is  accomplished  by  shutting 
off  the  steam  to  the  jacket  and  coils,  closing  the  valve  that  regulates 
the  water  supply  of  the  condenser,  stopping  the  vacuum  pump  and 
blowing  steam  direct  into  the  milk  in  the  pan,  for'the  purpose  of 
swelling  and  thickening  it.  During  this  process  the  vacuum  drops  to 
about  six  inches  of  the  mercury  column  and  the  temperature  rises 
to  between  180  and  200  degrees  F.  \Mien  the  milk  has  become 
sufficiently  thick  or,  in  the  language  of  the  processor,  has  produced 
the  "proper  liver"  ( coagulum )  the  steam  is  shut  off,  water  is  again 
turned  into  the  condenser  and  the  vacuum  pump  is  started  up.  As 
soon  as  the  vacuum  has  risen  to  twenty-five  to  twenty-six  inches 
and  the  temperature  has  dropped  to  about  130  degrees  F.  the  pro- 
cess is  complete,  the  vacuum  is  released  and  the  condensed  milk  is 
dFawn  off.  The  superheating  occupies  about  twenty-five  to  thirty 
minutes.  ^ 

Striking. — The  striking,  or  sampling  and  testing  for  gravity  is 
done  with  the  same  Beaume  hydrometer  that  is  used  for  evaporated 
milk.     The  batch  should   be  struck  before  and  after  superheating. 

Ratio  of  Concentration. — The  ratio  of  concentration  varies 
largely  with  the  fat  content  of  the  milk,  although  the  locality  and 
season  of  year  are  also  influencing  factors.  Whole  milk  is  con- 
densed at  the  ratio  of  about  three  parts  of  milk  to  one  part  of  con- 
densed milk,  wdiile  the  ratio  of  concentration  for  skim  milk  is  about 
4  to  I.  The  proper  density  varies  somewhat  with  locality  and 
reason  of  year.  Roughly  speaking,  whole  milk  has  reached  the 
proper  density  when  the  Beaume  reading  at  120  degrees  F.  is  about 
10  degrees  B.  and  skim  milk  has  reached  about  the  proper  density 
when  the  Beaume  reading  at  120  degrees  F.  is  about  14  degrees  B. 


102  CoNDKNSKD  Milk  and  Milk  Powder 

If  the  ratio  of  concentration  exceeds  4:1  there  is  danger  of  gritty 
milk,  due  to  the  precipitation  of  crystals  of  milk  sugar. 

Cooling. — The  plain  condensed  bulk  milk  is  drawn  into  40-quart 
cans,  placed  in  cooling  tanks  as  described  in  Chapter  \'I,  under 
"Cooling  of  Sweetened  Condensed  Milk,"  and  cooled  to  as  near 
the  freezing  point  as  facilities  will  permit.  The  product  is  then 
ready  for  the  market.  If  held  in  the  factory,  it  should  be  placed  in 
a  cold  room  or  should  be  otherwise  protected  against  souring.  If 
transported  long  distances  it  should  be  shipped  in  refrigerator  cars. 

CHAPTER   XIV 

CONCENTRATED  MILK 

Definition. — Concentrated  milk  is  cow's  milk,  either  whole  milk, 
or  partly  or  wholly  skimmed  milk,  condensed  at  the  ratio  of  three 
to  four  parts  of  fresh  milk  to  one  part  of  concentrated  milk.  It  is 
not  condensed  in  vacuo,  but  in  open  vats  by  pas.sing  currents  of  hot 
air  through  the  milk.  It  is  sold  largely  in  pint  and  quart  bottles  for 
direct  consumption.  It  is  not  sterile  and  therefore  keeps  for  a 
limited  time  only.  Its  keeping  quality  is  similar  to  that  of  a  high 
grade  of  properly  pasteurized  milk.  The  process  by  which  the  con- 
centrated milk  is  manufactured  is  known  as  the  "Campbell  Process." 
This  process  was  invented  by  J.  H.  Campbell  of  New  York  City,  in 
1900  and  patented  in  1901. 

Apparatus  Needed. — The  principal  parts  are :  the  evaporating 
vat  with  hot  water  jacket  and  coils,  and  air  blast  registers  or  noz- 
zles near  the  bottom  of  the  tank ;  an  air  blower  which  furnishes  the 
air  blast ;  an  air  heater  through  which  the  air  blast  passes  and  from 
which  the  heated  air  is  conducted  into  the  milk ;  a  water  pump  cir- 
culating hot  water  through  the  jacket  and  coils;  an  auxiliary  evap- 
orating tank  for  completing  the  evaporation ;  and  a  spray  pump 
which  throws  the  spray  of  milk  drawn  from  the  bottom  of  the  main 
evaporating  vat  into  that  tank  and  for  transferring  the  partly  con- 
densed milk  from  tank  i  to  tank  2. 

Operation  of  Campbell  Process. — The  milk  is  heated  to  about 
100  degrees  F.  and  allowed  to  How  into  evaporating  tank  i.  Water 
at  temperatures  ranging  from  lOO  to  125  degrees  F.  is  forced  through 


Condensed  Milk  and  Milk  Powder  103 

the  coils  and  jacket.  Hot  air  is  then  passed  into  the  milk.  The 
temperature  of  the  air  is  regulated  so  as  to  keep  the  temperature  of 
the  evaporating  milk  down  to  120  degrees  F.  on  the  start,  and  to 
finish  the  evaporation  between  90  and  100  degrees  F.  The  air 
blast  is  so  introduced  as  to  keep  the  milk  along  the  heating  surface 
of  the  jacket  and  coils  in  circulation  and,  therefore,  prevent  largely 
the  baking  of  the  milk  on  the  heating  surface.  After  the  milk  has 
been  evaporated  to  a  certain  degree  of  concentration,  say  2:1,  it  is 
transferred  to  the  auxiliary  evaporating  tank  where  the  condensa- 
tion is  completed.  This  transfer  is  not  necessary,  but  is  resorted 
to  solely  as  a  convenience,  in  order  to  continue  treatment  of  the  re- 
duced bulk  of  material  in  a  smaller  tank  and  leave  the  larger  tank 
free  for  treating  a  fresh  batch  of  milk,  and,  further,  because  there 
are  no  obstructing  coils  in  the  auxiliary  tank,  interfering  with  the 
drawing  off  of  the  finished  and  thick  condensed  milk.  In  this  pro- 
cess, as  now  used,  the  milk  is  usually  first  sq^aratcd  and  the  skim 
milk  only  is  condensed.  The  cream  is  subsequently  added  to  the 
condensed  skim  milk. 

Advantages  and  Disadvantages  of  Campbell  Process. — The 

initial  cost  of  installing  the  necessary  machinery  is  much  less  than 
where  vacuum  evaporation  is  practiced.  The  low  heat  applied  makes 
it  possible  for  the  finished  product  to  retain  the  properties  of  raw 
milk,  leaving  the  albumenoids  and  lime  salts  in  their  original  and 
easily  digestible  form. 

This  process  is  applicable  only  in  the  manufacture  of  unsweet- 
ened condensed  milk.  Unless  subsequently  sterilized,  the  product 
will  keq)  for  a  short  time  only.  This  process  has  at  the  present  time 
only  very  limited  use.  It  can  hardly  be  considered  as  an  important 
branch  of  the  condensed  milk  industry. 

CHAPTER    XV 

CONDENSED  BUTTERMILK 

The  value  of  buttermilk  as  a  chicken  feed  is  rapidly  gaining 
recognition.  lUittermilk,  similar  to  skim  milk  and  whole  milk,  is  a 
highly  satisfactory  feed  for  fattening  chickens.  Its  value  is  en- 
hanced by  the  superior  quality  of  the  meat  from  buttermilk-fed 
chickens. 


I04  Condensed  Milk  and  Milk  Powder 

Since  the  great  bulk  of  butter  is  manufactured  during  the  sum- 
mer season  the  main  supi^ly  of  buttermilk  is  confined  to  the  summer 
months.  In  summer  the  output  of  buttermilk  far  exceeds  the  de- 
mand for  this  product  and  much  of  it  goes  to  waste  for  lack  of  a 
suitable  market  for  it.  In  winter,  on  the  other  hand,  the  output  of 
buttermilk  is  small  and  insufficient  to  supply  the  demand. 

In  order  to  stop  this  waste  of  buttermilk  in  summer,  to  utilize 
it  economically  and  profitably  and  to  equalize  the  supply  throughout 
the  year,  some  of  the  large  creameries  of  the  country  have  found 
it  practicable  and  profitable  to  condense  the  surplus  buttermilk. 
Information  from  chicken  feeders  shows  that,  when  re-diluted  to 
the  consistency  of  the  original  buttermilk,  this  condensed  buttermilk 
gives  equally  as  satisfactory  results  as  the  fresh  buttermilk. 

Manufacture. — Buttermilk  is  condensed  in  vacuo  in  the  same 
manner  as  plain  condensed  bulk  milk,  or  in  open  vats  by  passing  a 
current  of  hot  air  through  it,  similar  as  in  the  case  of  concentrated 
milk.  The  latter  process  has  the  advantage,  because  it  involves  but 
little  additional  equipment  by  the  creamery  and  can  readily  be  oper- 
ated by  the  usual  creamery  personnel.  The  ratio  of  concentration 
is  about  4  to  5.5:1  ;  i.  e.,  from  four  to  five  and  five-tenths  parts  of 
buttermilk  are  condensed  to  one  part  of  condensed  buttermilk. 

The  Use  of  Ne^utralizErs  in  the  Manufacture  of  Con- 
densed Buttermilk. — The  condensed  buttermilk  has  a  grainy  body. 
This  is  due  to  the  action  of  acid  and  heat  on  the  casein,  contract- 
ing the  curd  and  making  it  hard,  dry  and  grainy.  If  the  acid  in  the 
buttermilk  is  neutralized  by  an  alkali  the  body  of  the  condensed  but- 
termilk is  smooth  and  homogeneous. 

The  most  common  alkalies  used  for  this  purpose  are  sodium 
bi-carbonate  and  milk  of  lime.  These  adulterants  are  easily  de- 
tected by  the  chemist.  In  order  to  more  successfully  hide  the  use 
and  presence  of  alkalies  in  condensed  buttermilk,  ammonium  hy- 
droxide and  ammonium  carbonate  are  frequently  employed  instead. 

Since  the  lactic  acid  in  the  buttermilk  is  one  of  the  desirable 
ingredients,  enhancing  its  wholesomeness  and  dietetic  value,  it  is 
obvious  that,  by  neutralizing  this  acid,  the  manufacturer  is  robbing 
his  product  of  one  of  the  chief  virtues  for  which  it  is  valuable. 

Furthermore,  while,  with  the  possible  exception  of  milk  of 
lime,  these  alkalies  add  nothing  to  the  milk  that  can  be  of  anv  benefit 


Condensed  Milk  and  Milk  Powder  '    105 

to  the  product  as  a  food,  the  addition  of  caustic  alkalies  in  quanti- 
ties sufficient  to  neutralize  most  of  the  acid  in  buttermilk  is  detri- 
mental to  the  wholesomeness  of  the  finished  product. 

Finally,  there  is  no  good  reason,  why  the  grainy  condensed  but- 
termilk should  be  less  acceptable  to  the  consumer  or  the  chicken 
feeder  than  a  paste-like  product  with  a  smooth  body. 

Chemical  Composition  of  Condensed  Buttermilk. — The  com- 
position of  condensed  buttermilk  naturally  varies  with  the  compo- 
sition of  the  original  buttermilk  and  the  degree  of  concentration. 
Since  these  two  factors  are  not  constant,  the  composition  of  the 
finished  product  may  vary  within  comparatively  wide  limits. 

The  following  analyses  show  the  composition  of  two  samples 
of  condensed  buttermilk : 

Composition  of  Condensed  Buttermilk 


Not 

Partly  neutralized  by 

neutralized 

ammonium  hydroxide 

Total  solids 

51-48 

40.90 

Moisture 

48.52 

59.10 

Ash 

3-93 

3-70 

Curd 

18.^3 

15-38 

Lactose 

26.30 

15-76 

Lactic  acid 

3.60 

2.52 

Ammonium 

hydroxide 

.00 

.88 

Total  101.28  97-34 

Uses  of  Condensed  Buttermilk. — Most  of  the  condensed  but- 
termilk is  sold  to  chicken  feeders.  It  brings  from  four  to  six  cents 
per  pound. 

Condensed  buttermilk  has  also  found  a  limited  demand  as 
human  food.  It  is  claimed  to  be  a  most  wholesome,  readily  digest- 
ible, nutritious  and  palatable  food.  Its  wholesomeness  and  digest- 
ibility are  attributed  to  its  high  lactic  acid  content.  It  is  best  put 
on  the  market  in  glass  bottles.  Its  keeping  quality  is  enhanced  by 
the  high  per  cent,  of  lactic  acid  it  contains. 


io6  Condensed  Milk  and  Milk  Powder 

CONDENSED  WHEY,  MYSEOST,  OR  PRIMOST 

The  condensing  of  whey  is  a  practice  which  originated  in 
Scandinavia.  The  original  process  consisted  of  straining  the  whey 
into  a  kettle  or  large  open  pan  over  a  fire.  "^The  albuminous  ma- 
terial that  precipitates  and  rises  to  the  surface  is  skimmed  off."  The 
whey  is  evaporated  as  rapidly  as  possible  with  constant  and  thorough 
stirring.  When  it  has  reached  about  one-fourth  of  its  original  vol- 
ume the  albumin  previously  skimmed  off  is  returned  and  stirred 
thoroughly  to  break  up  all  possible  lumps.  When  the  whey  has 
attained  the  consistency  of  thickened  milk  it  is  poured  quickly  into 
a  wooden  trough  and  stirred  with  a  paddle  until  cool,  to  prevent 
the  formation  of  large  sugar  crystals.  It  can  then  be  molded 
into  the  desired  form  for  market. 

A  more  rapid  method  of  making  primost  is  to  evaporate  the 
whey  in  the  vacuum  pan.  When  the  syrup  has  reached  the  desired 
density  it  is  drawn  off,  allowed  to  cool  and  pressed  into  bricks.  The 
product  has  a  yellowish  brown  color,  gritty  te.xture  and  sweetish 
taste. 

The  evaporation  of  whey  in  vacuo  is  as  yet  a  rare  practice  and 
the  demand  for  the  finished  product  is  very  limited. 


United  States  Department  of  Agriculture,  Bureau  of  Animal  Industry,  Bulletin  No.  105 


Condensed  Milk  and  Milk  Powder  107 


PART    IV 

FROM  FACTORY  TO  CONSUMER 

CHAPTER   XVI 
STAMPING 

Every  well  regulated  condensing  factory,  selling  condensed  milk 
in  hermetically  sealed  tin  cans,  employs  some  system  of  marking 
the  cans.    This  is  important  for  future  reference. 

When  defective  condensed  milk  is  returned  to  the  factory,  the 
marks  on  the  cans  tell  the  manufacturer  the  date  of  manufacture, 
and  his  own  record  on  file  in  the  factory  shows  the  conditions  under 
W'hich  the  defective  milk  was  made.  In  this  way  defects  can  usually 
be  traced  to  their  causes  and  the  recurrence  of  similar  trouble  can 
be  avoided. 

In  some  factories  the  batches  of  condensed  milk  are  numbered 
from  one  up,  and  the  cans  are  stamped  with  the  respective  batch 
number.  This  method  is  simple  but  may  prove  undesirable,  since 
it  informs  the  competitors  also  of  the  date  of  manufacture  of  com- 
peting brands.  In  most  factories  a  code  of  letters  and  figures  is 
used,  designating  the  factory,  the  date  and  the  number  of  the  batch 
of  each  day.  Thus  for  instance :  a  concern  has  three  factories,  A, 
B  and  C.  X  stands  for  the  current  year,  the  letters  E,  F,  G,  H,  I, 
J,  K,  L,  M,  N,  O,  P  indicate  the  twelve  months  of  the  year,  re- 
spectively, the  figures  i,  2,  3,  4,  etc.,  represent  the  day  of  the  month 
and  also  the  batches  of  condensed  milk  made  in  one  day. 

Example :  A  can  of  condensed  milk  belongs  to  the  second  batch 
made  Ai>ril  9,  1913,  at  factory  B.  The  can  would  be  stamped  as 
follows :     B  9  H  X  2. 

The  cans  are  usually  stamped  on  the  bottom,  that  is,  on  the 
end  which  carries  the  cap.  The  stamping  is  done  by  the  sealer. 
Small  interchangeable  rubber  letters  and  figures  are  used.  The 
stamping  ink  should  contain  a  drier  and  be  waterproof.  In  small 
factories  the  stamping  is  done  by  hand.    It  can  be  done  very  rapidly. 


io8  Condensed  Milk  and  Milk  Powder 

In  large  factories  an  automatic  stamping  outfit  is  attached  to  the 
filling,  sealing  or  labeling  machine  and  the  cans  are  stamped  auto- 
matically while  they  are  being  filled,  sealed,  or  labeled. 

INSPECTING 

iThe  sealed  and  stamped  cans  are  placed,  with  caps  down,  in 
wooden  trays  holding  twenty-four  medium  sized  cans.  All  trays  of 
one  batch  are  stacked  together.  A  card  indicating  number  and  date 
of  batch  and  number  of  cans  in  the  batch  is  attached  to  the  stack 
and  a  copy  of  the  same  is  filed  in  the  office.  The  cans  are  placed 
with  their  caps  down  in  order  to  detect  "leakers"  (cans  with  de- 
fective seals).  Before  labeling,  the  trays  should  be  taken  down,  the 
cans  turned  over  and  examined  for  leaky  seals.  Unless  the  factory 
is  behind  in  filling  orders  the  cans  will  have  been  in  stock  at  least 
twenty- four  hours  or  usually  longer.  In  the  case  of  sweetened  con- 
densed milk,  if  any  seals  are  defective,  a  little  condensed  milk  will 
have  oozed  out  by  that  time.  Inexiperienced  sealers  are  prone  to 
cause  a  high  percentage  of  leaky  cans.  A  careful  sealer  may  reduce 
the  number  of  leakers  to  .i  per  cent. 

Checking  the  Work  of  the  Sealers. — In  order  to  regulate  and 
improve  the  work  of  the  sealers  and  to  locate  those  doing  poor  work, 
it,  is  advisable  to  number  the  sealers  and  supply  each  with  small  tin 
tags  bearing  his  or  her  respective  number.  Each  sealer  drops  one 
tag  into  each  tray  of  cans  sealed  by  him.  The  inspectors  record 
the  number  of  leakers  found  in  each  tray.  Thus  each  sealer  is 
charged  up  with  the  leakers  he  made. 

Disposition  of  Leaky  Cans. — Small  leaks,  in  the  case  of  sweet- 
ened condensed  milk,  can  usually  be  soldered  over  successfully  and 
the  mended  cans  are  returned  to  their  respective  batches.  In  the 
case  of  very  defective  seals,  attempts  at  mending  generally  cause  the 
milk  in  the  can  to  burn,  forming  a  brown  crust  on  the  cap,  which 
spoils  the  can  for  the  market.  The  contents  have  a  burnt  taste  and 
smell,  and  upon  stirring,  brown  and  black  specks  of  burnt  milk  ap- 
pear. It  is  best  to  cut  bad  leakers  open  and  pour  the  contents  into 
the  succeeding  batch  of  milk. 

Importance  of  Inspection. — The  above  description  of  inspec- 
tion refers  to  sweetened  condensed  milk.    This  work  is  neglected  in 


Condensed  Milk  and  Milk  Powder  109 

many  factories,  though  it  is  very  important.  It  may  save  labels  and 
boxes,  as  well  as  much  unnecessary  labor  in  unpacking  cases  with 
leaky  cans,  and  washing,  relabeling  and  repacking  them  in  new, 
clean  cases. 

In  the  case  of  evaporated  milk  (unsweetened,  sterilized)  all  cans 
coming  from  the  incubating  room  should  be  individually  shaken  by 
hand.  All  cans  showing  no  signs  of  bulging,  and  the  contents  of 
which  shake  with  the  characteristic  sound  and  behavior  of  a  liquid, 
pass  inspection.  If  the  ends  of  the  cans  are  bulging  or  the  contents 
do  not  respond  to  the  shaking  with  the  characteristic  sound  of  nor- 
mal milk,  they  are  rejected,  as  the  evaporated  milk  in  them  has 
either  undergone  gaseous  or  curdling  fermentation,  and  is  spoiled. 

LABELING 

Labeling  Machines. — In  the  early  days  of  the  milk  condensing 
industry,  the  labeling  of  the  cans  was  done  by  hand,  involving  much 


Fig.  i"*-     A  very  satitifa^-tory  labeling;  machine 

Courtesy   of  Burt   Machine   Co. 

time  and  considerable  expense.  Today,  especially  constructed  label- 
ing machines  are  almost  exclusively  used  for  this  purpose.  The 
efficiency  of  these  machines  is  such,  that  they  have  become  a  perma- 
nent fixture  in  practically  every  condensery  selling  canned  goods. 
They  are  adjustable  to  various  sizes  of  cans  and  can  be  operated  by 
hand,  motor  or  belt  power. 

Principle  of  Labeling  Machines. — The  cans  are  placed  into  a 
chute  from  which  they  roll  into  the  machine  by  gravity.  They  are 
caught  by  two  endless  belts  which  draw  them  through  the  machine. 


iio  Condensed  Milk  and  Milk  Powder 

They  hrst  pass  over  the  paste  box,  which  contains  an  automatically 
revolving  wheel  covered  with  a  thick  layer  of  felt.  The  felt  is  sat- 
urated with  paste  or  glue  from  the  paste  box.  Each  can  comes  in 
contact  with  the  paste  wheel  and  receives  a  touch  of  paste.  Then 
the  cans  pass  over  the  label  box  containing  a  stack  of  labels,  face 
down.  Each  can  picks  up  one  label  which  is  automatically  wrapped 
around  the  can  as  it  runs  through  the  machine.  The  label  box  is 
equipped  with  an  automatic  feeder  which  pushes  the  labels  up  as 
fast  as  they  are  being  used.  The  labeled  cans  leave  the  machine 
over  a  chute  which  slants  from  it.  As  they  are  removed  they  are 
packed  directly  into  cases. 

Wrinkles  and  Rust  Spots  on  Labels. — The  attractiveness  of 
the  package  depends,  largely,  on  the  neatness  of  the  label.  The 
use  of  too  thin,  too  thick,  or  too  much  paste  causes  the  labels  to 
wrinkle  on  the  cans.  The  paste  should  have  the  consistency  of 
heavy  dough  and  the  paste  wheel  should  be  so  adjusted  that  it  barely 
touches  the  passing  cans. 

Frequently  the  labels  of  the  cans  show  stains  and  spots.  This 
is  especially  true  in  the  case  of  old  goods,  and  is  due  either  to  a 
poor  quality  of  paper,  the  use  of  sour  paste  or  the  storing  of  the 
labeled  goods  in  damp  places.  Sour  paste  corrodes  the  cans  and 
causes  them  to  rust.  The  rust  penetrates  the  label  and  spoils  the 
appearance  of  the  package.  Trouble  of  this  kind  can  be  avoided 
by  preparing  fresh  paste  every  day.  Paste  saved  from  the  previous 
day  is  prone  to  sour  and  should  not  be  used.  The  storing  of  the 
labeled  goods  in  damp  places  also  often  causes  rust  spots  as  well  as 
moulds  on  the  labels.  Thin  and  soft  paper  labels  more  easily  than 
thick,  stiff  and  glossy  paper.  In  the  latest  types  of  labeling  machines 
the  use  of  ordinary  paste  has  been  largely  superseded  by  that  of 
specially  prepared  glue,  which  removes  most  of  the  objectionable 
features  of  the  ordinary  paste,  does  not  damage  the  label  and  makes 
a  neater  package. 

PACKING 

The  labeled  cans  are  packed  in  cases  holding  from  six  to  ninety- 
six  cans,  according  to  the  size  of  the  cans.  (One  case  holds  six 
i-gallon  cans;  forty-eight  14-,  15-,  16-,  and  20-ounce  cans;  or 
seventy-two  to  ninety-six  8-ounce  cans). 


Condensed  Milk  and  Milk  Powder  hi 

The  sides,  bottom  and  top  of  the  cases  should  be  of  material 
about  three-eighths  of  an  inch  to  one-half  inch  thick,  the  ends 
three-fourths  of  an  inch  to  seven-eighths  of  an  inch  thick.  The 
cases  are  usually  bought  in  the  "knock-down"  shape  and  are  made 
up  in  the  factory.  Sixpenny  cement-coated  wire  nails  are  most 
suitable  for  this  purpose.  The  cases  are  most  economically  nailed 
by  the  use  of  nailing  machines,  which  nail  one  entire  side  or  one 
side  and  one  end  simultaneously.  The  cans  are  usually  placed  into 
the  cases  direct  from  the  labeling  machine.  In  some  factories,  pack- 
ing machines,  which  pack  twenty-four  medium-size  cans  in  one 
operation,  are  used. 

Marking  the  Cases. — Qne  end  of  each  case  is  stenciled  with  the 
number  of  the  batch ;  over  the  other  end  is  pasted  a  case  label,  rep- 
resenting, enlarged,  the  brand  of  the  label  on  the  cans  within.  In 
the  place  of  the  case  label,  the  respective  brand  may  be  printed  on 
or  burnt  into  the  wood.  The  burnt  stencilling  is  usually  done  by  the 
manufacturer  of  the  shooks.  One  side  of  each  case  is  usually 
marked  "Condensed  Milk"  or  "Evaporated  Milk."  as  the  case  may 
be;  the  other  "Keep  in  cool,  dry  place."  If  sweetened  condensed 
milk  is  exposed  to  excessive  heat  for  a  considerable  length  of  time, 
as  is  often  the  case  in  storehouses  or  in  the  hold  of  steamers,  where 
the  cases  may  be  stowed  against  the  boiler  room,  it  becomes  brown, 
thickens  rapidly  and  develops  a  sta^e  flavor.  Evaporated  milk  also 
darkens  when  exposed  to  heat  and  depreciates  in  flavor.  It  should, 
therefore,  be  kept  in  a  cool  place.  The  humidity  of  the  storage  room 
has  no  eft'ect  on  the  condensed  milk  proper,  the  cans  being  hermet- 
ically sealed.  Prolonged  exposure  to  dampness,  however,  will  mois- 
ten the  paste  under  the  labels.  This  causes  the  labels  to  wrinkle  and 
the  paste  to  become  sour  and  musty.  The  sour  paste  corrodes  the 
cans  and  rust  spots  penetrate  the  labels.  Such  cans  also  may  soon 
become  coated  with  mildew. 

Packing  Condensed  Milk  for  Export. — In  the  case  of  con- 
densed milk  bought  by  the  United  States  Government,  the  cans  are 
dipped  in  a  solution  of  shellac  before  they  are  labeled.  Cans  for 
export  trade  and  in  many  instances  for  the  home  market,  are 
wrapped  into  heavy,  soft  paper,  bearing  on  the  outside  a  copy  of 
the  respective  brand.  This  wrapping  paper  takes  up  the  space  be- 
tween the  cans  and  prevents  the  cans  from  being  damaged  on  their 


112  Condensed  Milk  and  AIilk  Powder 

long  journey  and  by  rough  usage.  This  wrapping  is  usually  done 
by  hand.  Some  makes  of  labeling  machines,  however,  have  an  at- 
tachment for  wrapping  the  cans  so  that  when  the  cans  leave  the 
machine  they  are  wrapped  as  well  as  labeled.  The  cases  are  rein- 
forced with  a  band  of  strap  iron  around  each  end.  Where  the  cases 
have  to  be  loaded  and  unloaded  numerous  times,  as  is  the  case  with 
export  shipments,  they  are  in  danger  of  being  torn  to  pieces,  unless 
such  special  precautions  are  taken. 

CHAPTER  XMI 
STORAGE 

Purpose  of  Storing. — The  purpose  of  storing  condensed  milk 
is  largely  the  same  as  that  of  storing  butter .  and  other  produce, 
namely,  to  keep  the  product  from  the  time  of  large  supply  and  low 
prices,  to  the  time  of  small  supply  and  high  prices.  In  summer 
time,  the  market  is  usually  flooded  with  condensed  milk  throughout 
the  country,  the  demand  for  it  is  at  ebb  tide  and  the  prices  are  low. 
In  winter,  there  is  usually  a  great  shortage  of  condensed  milk, 
the  demand  far  exceeds  the  supply  and  prices  soar  high.  The 
storing  of  summer  milk  may  be  necessary,  also,  in  order  to 
enable  the  manufacturer  to  fill  his  contracts  and  supply  his  trade 
in  winter.  This  is  especially  trite  where  the  factories  of  a  concern 
are  "located  in  new  territories  where  the  patrons  produce  an  ex- 
cessively small  amount  of  winter  milk. 

Plain  condensed  milk  and  concentrated  milk  which  are  not 
sterile  and  contain  no  cane  sugar  to  preserve  them,  keep  but  a  few 
days  at  ordinary  temperatures  and  should,  therefore,  be  sold  and 
used  as  soon  as  possible  after  manufacture.  If  their  storage  is 
unavoidable,  they  should  be  held  as  near  the  freezing  point  as  pos- 
sible. For  prolonged  storage  it  might  be  advantageous  to  freeze 
them.  However,  reliable  data  on  this  phase  of  the  industry  are 
lacking. 

Evaporated  milk,  sold  in  hermetically  sealed  cans,  is  supposed 
to  be  entirely  sterile,  and,  if  made  properly,  will  keep  indefinitely. 
There  is  a  constant  tendency,  however,  for  the  fat  to  separate  out, 
which  naturally  is  augmented  by  prolonged  storage.  Again,  the 
lactic  acid  in  the  evaporated  milk  gradually  acts  on  the  can,  causing 


Condensed  Milk  and  Milk  Powder  113 

the  tinplate  to  become  dull  and  the  contents  to  acquire  a  disagree- 
able metallic  flavor.  When  stored  for  an  excessively  long  time  this 
chemical  action  may  be  sufficient  to  cause  the  evolution  of  consider- 
able quantities  of  hydrogen  gas,  swelling  the  cans. 

Sweetened  condensed  milk  which  is  preserved  by  about  40  per 
cent,  of  sucrose,  will  keep  apparently  unchanged  for  a  considerable 
length  of  time.  It  is  best,  however,  when  fresh.  Bacteriological 
examinations  have  shown  that,  while  moderate  age  does  not  change 
the  outward  appearance  of  this  condensed  milk,  the  bacteria  in  it 
gradually  increase  and  the  milk  gradually  develops  a  stale  flavor. 
White  and  yellow  "buttons,"  lumps,  or  nodules  of  a  cheesy  texture 
and  flavor,  probably  due  to  some  fungus  growth,  are  also  prone  to 
appear  in  the  condensed  milk.  Age,  also,  causes  it  tO'  become  darker 
in  color.  These  defects  are  especially  apparent  in  old  milk  which 
has  not  been  kept  at  a  low  temperature.  Again,  sweetened  con- 
densed milk  made  in  May  and  June  has  a  strong  tendency  to  thicken 
with  age  and  to  become  entirely  solid. 

In  some  cases  a  part  of  the  sweetened  condensed  milk  made 
during  the  summer  months  is  stored  in  large  cylindrical  wooden  or 
iron  tanks  sunk  into  the  ground,  or  installed  in  the  basement  of  the 
factory,  where  the  condensed  milk  remains  at  an  even  temperature. 
As  the  demand  for  the  product  increases  and  the  supply  of  fresh 
milk  decreases,  condensed  milk  is  drawn  from  these  tanks  to  fill  the 
increasing  orders. 

Effect  of  Storage  Temperature. — Most,  if  not  all  the  changes 
which  condensed  milk  is  prone  tO'  undergo  in  storage  are  retarded, 
if  not  entirely  prevented,  when  stored  at  the  proper  temperature. 
Temperatures  of  60  degrees  F.  or  above  are  too  high  for  satisfactory 
storage  for  a  prolonged  period  of  time  and  the  higher  the  temper- 
ature the  greater  the  resulting  defect. 

Temperatures  below  the  freezing  point  of  water  are  also 
undesirable.  The  evaporated  milk  freezes  and  while  so  doing  it 
expands  sufficiently  to  swell  the  can?.  Although  this  swelling  dis- 
appears when  the  contents  of  the  cans  dissolve  again,  yet  the  swell- 
ing action  tends  to  weaken  the  cans  and  may  give  rise  to  subsequent 
leakers.  Again  the  melted  evaporated  milk  is  prone  to  be  grainy  as 
the  result  of  freezing.  This  is  due  to  the  fact  that  when  freezing, 
the  watery  portion  separates  from  the  curd  and  the  latter  contracts. 


114 


Condensed  Milk  and  Milk  Powder 


When  the  milk  thaws  up  the  curd  remains  contracted  and  fails  to 

form  a  smooth  emulsion  with  the  remainder  of  the  milk. 

The    sweetened    condensed    milk    does    not    freeze,    because    it 

contains  so  concentrated  a  sugar  solution  that  its  freezing  point  is 
usually  far  below  the  refrigerating  tem- 
perature. If  it  is  packed  in  solder-sealed 
cans  there  is  usually  no  bad  effect  from 
cold  storage.  However,  when  packed  in 
cans  sealed  with  the  friction  cap  or  the 
burr  cap,  difficulties  may  arise.  These 
seals  are  not  air-tight.  Excessively  low 
storage  temperatures  cause  the  contents 
to  shrink  appreciably.  Suction  is  formed 
and  air  is  drawn  in  through  the  seal. 
When  these  cans  again  warm  up,  the  vis- 
cous milk  in  the  cans  seals  the  micro- 
scopic openings,  the  air  and  the  liquid 
expand  but  the  air  finds  no  exit.  This 
causes  the  cans  to  swell.  \\'hile  the 
quality  of  the  milk  in  these  cans  is  not 
impaired   in  the  least,  the   swelled  cans 

suggest  gaseous  fermentation,  which  means  spoiled  milk  and  which 

is  invariably  rejected  on  the  market. 

The  temperatures  at  which  condensed  milk  can  be  stored  with 

the  least  objectionable  results,  range  between  32  and  50  degrees  F. 

Advisability  of  Storing. — A  heavy  stock  of  condensed  milk  is 
a  severe  drain  on  the  working  capital  of  the  condensery,  involving 
the  cost  of  the  fresh  milk,  cane  sugar,  tinplate,  boxes,  solder,  labels, 
coal  and  labor. 

Unless  the  manufacturer  has  successfully  overcome  and  mas- 
tered all  of  the  principal  condensed  milk  defects,  and,  unless  his 
experience  justifies  him  in  believing  that  his  goods  will  stand  the 
trials  of  storage,  he  will  find  it  advisable  not  to  manufacture  more 
than  he  can  promptly  dispose  of.  Even  at  best,  the  condensed  milk 
will  be  from  three  to  six  months  old  before  it  is  all  consumed,  and, 
if  it  is  at  all  subject  to  deterioration,  the  sooner  it  is  consumed 
the  better. 

But  even  if  the  condensed  milk  comes  out  'of  storage  in  good 


Fig.  48.     The  Stevenson  door 

Courtesy   of  Stevenson    Co. 


Condensed  Milk  and  Milk  Powder  115 

condition,  the  condition  of  the  market  may  'be  such  that  the  goods 
cannot  be  sold  at  a  profit,  and  if  the  market  happens  to  take  a 
demoraHzing  skimp,  at  the  time  the  goods  are  ready  to  leave  the 
storage,  the  manufacturer  may  suffer  heavy  loss.  This  condition 
has  occurred  repeatedly  within  the  last  ten  years. 

TRANSPORTATION 

The  plain  condensed  bulk  milk  and  concentrated  milk  are  highly 
perishable  products.  If  shipped  considerable  distances  they  should 
be  placed  in  refrigerator  cars. 

The  evaporated  milk  and  sweetened  condensed  milk  in  hermet- 
ically sealed  cans,  and  the  latter  also  in  barrels,  can  safely  be  shipped 
in  ordinary  box  cars.  The  cases  weigh  from  fifty  to  sixty-five 
pounds,  and  the  barrels  from  three  hundred  to  seven  hundred 
pounds.  Care  should  be  taken  that  .the  cars  used  for  this  purpose 
are  clean  and  did  not  previously  carry  goods  with  strong  and  ob- 
noxious odors,  such  as  fertilizers,  as  these  odors  are  prone  to  follow 
the  condensed  milk  to  its  destination.  Strong  box  cars,  in  good 
repair  only,  should  be  used.  Even  at  best,  the  cases  and  cans  suffer 
more  or  less  damage  in  transportation.  Cars  with  leaky  roofs 
should  be  condemned,  as  transportation  in  them  may  cause  the 
package  to  suffer  in  appearance.  If  shipped  on  steamboats,  it  should 
be  specified  to  stow  the  cases  away  from  the  boiler  room,  as  pro- 
longed exposure  to  high  temperatures  causes  the  condensed  milk 
to  deteriorate. 

CHAPTER  XVIII 
MARKETS 

A  large  proportion  of  the  canned  condensed  milk,  both  sweet- 
ened and  unsweetened,  supplies  localities,  territories  and  countries 
where  the  dairy  industry  is  yet  in  its  infancy,  or  where  geographic 
and  climatic  conditions  bar  the  profitable  husbandry  of  the  dairy 
cow.  Thus,  we  find  some  of  the  best  condensed  milk  markets  in 
the  tropics,  in  the  arctic  regions,  in  the  army  and  navy,  on  ocean 
liners  and  in  mining  and  lumber  camps.  In  these  markets  condensed 
milk  has,  in  many  cases,  become  as  great  a  necessity  as  fresh  milk 
is  to  the  inhabitants  within  the  temperate  zone.     The  consumption 


ii6  Condensed  Milk  and  Milk  Powder 

of  canned  condensed  milk  in  our  home  markets  has.  also,  been  in- 
creasing rapidly  within  recent  years,  and  is  today  assuming  aston- 
ishing proportions.  The  rapid  growth  of  the  ice  cream  industry 
has  further  developed  a  splendid  and  ever  increasing  market  for 
plain  condensed  bulk  milk. 

It  is  estimated  that  the  canned  condensed  milk  is  from  three 
to  six  months  old  before  it  reaches  the  consumer.  It  is  usually  sold 
through  the  medium  of  a  jobber  or  broker  and  not  direct  from 
manufacturer  to  consumer.  In  its  transit  to  the  distant  markets,  it 
is  subjected  to  many  delays;  first,  by  its  storage  in  the  factory,  then 
the  time  in  transportation,  next,  the  delay  in  the  warehouse  of  the 
jobber,  broker  or  wholesale  dealer.  From  there  it  gradually  finds 
its  way  to  the  shelves  of  the  retailer,  where  there  is  again  consider- 
able delay  before  it  reaches  the  pantry  of  the  consumer. 

Market  Prices  of  Condensed  Milk. — The  price  of  condensed 
milk  is  not  controlled  by  the  general  market  of  dairy  products,  nor 
by  any  board  of  trade ;  there  is  no  consistent  uniformity  of  price 
throughout  the  country  as  is  the  case  of  butter  and  cheese.  The 
price^  of  condensed  milk  does  not  necessarily  follow  the  rise  and 
fall  of  the  butter  and  cheese  markets,  but  in  the  long  run  it  is 
usually  affected  by  abrupt  fluctuations  of  the  prices  of  these  other 
dairy  products,  largely  on  account  of  the  influence  of  such  fluctua- 
tions on  the  supply  to  the  condensery  of  fresh  milk.  It  is  chiefly 
governed  by  local  conditions  of  supply  and  demand,  composition  of 
product  and  reputation  of  the  individual  brand.  Condensed  milk 
is  sold  under  hundreds  of  different  brands  or  labels.  While  one  and 
the  same  concern  may  sell  scores  of  different  brands,  the  brand- 
itself  has  very  little,  if  anything,  to  do  with  the  quality  or  com- 
position of  the  contents  of  the  can.  Each  brand  usually  sells  at  its 
own  special  price,  although  the  various  brands  put  on  the  market 
by  the  same  concern  often  contain  the  same  quality  of  milk  and  may 
be  filled  with  condensed  milk  from  one  and  the  same  batch.  It  is 
customary  in  most  factories  to  fill  the  cans  before  they  are  labeled 
and  the  orders  for  different  brands  of  condensed  milk  are  filled 
from  the  same  general  stock.  The  brands  serve  largely  as  an  in- 
strument to  increase  the  sales  and  to  "dodge"  competitors. 

Sweetened  condensed  milk,  packed  in  hermetically  sealed  cans, 
sells  from  about  $3.25  to  $5  per  case  of  48  sixteen-ounce  cans  and 


Condensed  Milk  and  Milk  Powder  117 

the  cans  retail  at  from  5  to  20  cents  each,  according  to  the  size  of 
the  cans  and  market  conditions. 

Evaporated  milk,  unsweetened  condensed  milk  in  hermetically 
sealed  cans,  sells  from  S2.25  to  $4.00  per  case,  according  to  the  size 
of  the  cans  and  market  conditions. 

Bulk  milk,  both  sweetened  and  unsweetened,  goes  direct  from 
the  manufacturer  to  the  purchaser  who  uses  it  at  prices  agreed  upon 
by  the  contracting  parties.  The  sweetened  condensed  milk  is  sold  in 
barrels  holding  from  three  hundred  to  seven  hundred  pounds 
(usually  about  six  hundred  pounds)  to  candy  and  caramel  factories, 
bakeries  and  confectioners.  The  price  varies  from  four  to  ten 
cents  per  pound  according  to  the  per  cent,  of  fat,  demand  and  sup- 
ply. When  there  is  a  general  "epidemic"  of  bad  canned  condensed 
milk,  as  is  the  case  in  years  when  the  price  of  sugar  is  high,  due  to 
failure  of  the  sugar  cane  crop,  and  many  manufacturers  are  tempted 
to  use  inferior  cane  sugar,  which  they  buy  at  a  comparatively  low 
cost,  this  spoiled  condensed  milk  is  usually  turned  into  candy  shops 
and  bakeries,  where  it  is  sold  for  "a  song."  This  condition  has 
always  a  depressing  influence  on  the  price  of  sweetened  condensed 
bulk  milk,  which,  during  such  seasons,  may  have  to  be  sold  at  a 
loss.  Some  milk  condensing  concerns  operate  their  own  candy 
shops  which  take  care  of  the  condensed  milk  that  is  rejected  on  the 
market. 

Plain  or  unsweetened  condensed  milk  is  sold  in  i -gallon  to 
10-gallon  cans  to  ice  cream  factories,  the  price  varying  from  twenty- 
five  to  ninety  cents  per  gallon,  according  to  fat  content,  concentra- 
tion and  market  conditions.  The  market  for  this  class  of  goods  is 
not  very  constant,  but  the  profits  are  generally  high.  It  reaches  ebb- 
tide in  winter  when  the  demand  for  ice  cream  is  small.  Limited 
quantities  of  plain  condensed  bulk  milk  are  also  sold  in  milk  and 
cream  bottles  for  direct  consumption.  The  concentrated  milk  finds 
the  same  markets  as  the  plain  condensed  bulk  milk. 

Exports  and  Imports. — Canned  condensed  milk  only  need  be 
considered  here. 

The  United  States  Bureau  of  Statistics  reports  the  following 
imports  and  exports  of  condensed  milk  for  the  year  1911^ 


1  United   States   Department   of  Commerce    and   Labor,   Bureau   of   Statistics,   Report 
for  1912 


ii8  Condensed  Milk  and  Milk  Powder 

Exports  and  Imports  of  Condensed  Milk  in  the  United  States  in  191 1 


Exports  and  imports 
in  1911 

Condensed  milk 

Pounds 

Dollars 

Duty  dollars 

Exports 
Imports 

12,180,445 
630,308 

936,105.00 
46,088.00 

12,606.00 

The  United  States  export  condensed  milk  chiefly  to  North 
America,  Oceanica,  and  Asia,  small  quantities  are  also  exported  to 
South  America,  Africa  and  Europe.  About  60  per  cent,  of  all  the 
export  condensed  milk  goes  to  countries  of  the  North  American 
Continent,  Canada  and  Panama  being  the  leading  markets.  Of  late 
years  our  exports  to  Canada  have  fallen  off  very  rapidly.  In  1911, 
the  total  exports  to  Canada  amounted  to  only  about  15  per  cent,  of 
the  total  exports  to  the  same  country  in  1908.  The  rapid  develop- 
ment of  the  milk  condensing  industry  in  Canada  within  the  last  few 
years  is  largely  responsible  for  this  condition.  The  total  exports  of 
the  United  States  are  decreasing  every  year.  In  1907,  they  amount- 
ed to  $2,191,000  as  against  $936,105  in  1911. 

The  imports  of  condensed  milk  in  the  United  States  are  very 
limited.  Condensed  milk  can  be  manufactured  in  this  country  prac- 
tically as  cheaply  as  anywhere  else.  The  availability  of  large  quan- 
tities of  cane  sugar,  which  can  be  purchased  practically  as  cheaply 
and  in  many  cases  more  cheaply  than  sucrose  in  foreign  lands,  the 
fact  that  prices  of  fresh  milk  in  America  compare  very  favorably 
with  those  elsewhere,  and  that  the  higher  cost  of  American  labor  is 
largely  offset  by  the  more  general  use  of  labor-saving  machinery, 
put  the  cost  of  manufacture  of  American  condensed  milk  practically 
on  a  par  with  that  of  other  countries.  The  high  protective  tariff 
on  imported  condensed  milk  is  an  additional  effective  agent  to 
exclude  foreign  brands  from  American  markets.  The  duty  on 
imported  condensed  milk  is  two  cents  per  pound  or  $1.00  per  case.^ 

Another  cause  of  the  limited  imports  lies  in  the  fact  that  the 
agreement  under  which  the  leading  European  milk  condensing  com- 
pany, the  .\nglo-Swiss  Condensed  Milk  Company,  which  consoli- 
dated with  the  Nestle  Condensed  Milk  Company,  in  1904,  and  sold 


1  In  Itns  the  UnittNl  .States  by  Act  of  Congress  removed  the  tariff  frcm  condensed  milk, 
so  that  forelKii  l>ranils  of  condense*!  milk  may  now  be  imported  free  from  duty 


Condensed  Milk  and  Milk  Powder  119 

its  American  factories  and  business  to  Borden's  Condensed  3>Iilk 
Company,  contains  a  clause  barring  that  company  from  American 
markets. 

CHAPTER  XIX 

CHEMICAL   COMPOSITION    OF    CONDENSED   MILK 

Sweetened  Condensed  Milk. — Sweetened  condensed  milk  con- 
tains all  the  constituents  of  fresh  milk  and  considerable  but  varying 
quantities  of  sucrose.  Its  composition,  therefore,  depends  on  such 
factors  as :  composition  of  the  fresh  milk  from  which  it  is  made ; 
the  degree  of  condensation  and  per  cent,  of  cane  sugar  added.  As 
all  of  these  factors  vary  in  milk  from  different  localities,  and  in 
milk  of  the  same  factory  at  different  seasons  of  the  year,  no  hard 
and  fast  rule  can  be  given.  The  following  figures  merely  show  the 
average  composition  of  sweetened  condensed  milk  as  ohtained  from 
the  results  of  analyses  of  a  large  number  of  different  brands. 

AVERAGE    COMPOSITION    OF    SWEETENED    CONDENSED    MILK 

Water  26.5  per  cent. 

fat  9.0  per  cent.  ^ 

proteids  8.5  per  cent. 

milk   sugar  13.3  per  cent. 

.  ash  1 .8  per  cent.  J 
Cane  sugar                                                                                40.9  per  cent. 


Milk  solids 


32.6  per  cent. 


Total  100.0  per  cent. 

W'.VTER. — The  water  content  is  largely  governed  by  the  degree 
of  condensation  and  the  per  cent,  of  cane  sugar.  American  brands 
average  from  24  per  cent,  to  28  per  cent,  water.  In  exceptional 
cases  milk  has  been  fcnuid  to  contain  as  low  as  21  per  cent,  and  as 
high  as  34  per  cent,  water. 

Milk  Solids. — The  per  cent,  of  milk  solids  is  largely  governed 
by  the  per  cent,  of  milk  solids  in  fresh  milk  and  the  degree  of  con- 
densation. In  the  majority  of  brands  the  solids  fluctuate  between 
30  and  34  per  cent.;  in  extreme  cases  analyses  have  shown  as  low 
as  28  per  cent,  and  as  high  as  40  per  cent,  milk  solids.  The  relative 
proportion  in  which  the  various  solid  constituents  are  present  is  the 
same  as  that  in  the  fresh  milk  from  which  the  condensed  milk  is 


I20  Condensed  Milk  and  Milk  Powder 

made,  provided  that  the  fresh  milk  was  not  skimmed  previous  to 
condensing. 

BuTTERFAT. — The  butter  fat  in  sweetened  condensed  whole  milk 
fluctuates  from  about  8  to  12  per  cent.,  according  to  locality,  season 
of  year  and  degree  of  condensation.  Sweetened  condensed  milk  sold 
in  barrels  is  usually  partly  or  wholly  skimmed  and  is,  therefore,  low 
in  fat.  It  has  been  suggested  that  a  small  portion  of  the  milk  fat  is 
lost  during  the  process  of  condensation,  and  this  theory  is  frequently 
resorted  to  by  condensed  milk  men  to  explain  why  their  milk  is  low 
in  fat.  It  has  been  claimed  by  some  that  the  volatile  fats  (volatile 
fatty  acids)  are  lost  during  the  process  of  condensation.  This  claim 
is  not  well  founded,  since  repeated  experiments^  have  conclusively 
demonstrated  that  condensed  milk  contains  the  normal  amount  of 
volatile  fatty  acids.  It  has  further  been  experimentally  proven  that 
the  condensed  milk,  when  made  properly  and  from  whole  milk, 
contains  fat  equal  in  amount  to  that  found  in  the  fresh  milk  used. 
A  reasonable  allowance  should  be  made,  however,  for  loss  of  milk 
due  to  spilling  and  wasting  in  pipes  and  retainers.  Experience  has 
shown  that  this  loss  amounts  to  about  fifty  to  one  hundred  pounds 
of  milk  per  average  batch  under  normal  conditions. 

ProTe^ids. — The  per  cent,  of  proteids  in  condensed  milk  varies 
with  the  per  cent,  of  proteids  in  the  original  milk  and  the  degree  of 
concentration.  It  fluctuates  usually  between  7.5  and  9  per  cent. 
The  heating  previous  to  condensing  coagulates  a  portion  of  the  milk 
albumin  and  alters  the  casein  to  the  extent  that  it  is  not  precipitated 
in  the  normal  way,  when  rennet  is  added  to  the  diluted  condensed 
milk.  In  early  spring  when  the  majority  of  the  cows  supplying  the 
condensery  freshen,  there  is  a  tendency  of  the  jacket  and  coils  in  the 
vacuum  pan  to  become  coated  more  or  less  heavily  with  a  layer  of 
semi-solid  milk.  This  very  probably  is  due  to  the  relatively  high 
per  cent,  of  albumin  which  sticks  to  the  heating  surface.  This 
thickened  milk,  when  mixed  with  and  stirred  in  water,  usually  re- 
dissolves  without  much  difficulty.  See  also  "Defects  of  Sweetened 
Condensed  Milk,"  page  151. 

While,  in  most  analyses  of  sweetened  condensed  milk,  the  per 
cent,  of  proteids  nearly  equals  that  found  in  the  fresh  milk  multi- 
plied by  the  degree  of  concentration,  there  is  a  tendency  toward  a 


Hunziker  and  Spitzer,  Indiana  Agricultural  Kxperiment  Station  Bulletin  No.  VM,  1909 


Condensed  Milk  and  Milk  Powder  121 

slight   loss   of   this    constituent   due   to   precipitation    in    the    fore- 
warmers. 

Milk  Sugar. — Sweetened  condensed  milk  contains  from  about 
12.5  to  15  per  cent,  of  milk  sugar,  the  amount  varying  according 
to  the  degree  of  concentration  and  per  cent,  of  milk  sugar  in  the 
fresh  milk.  The  milk  sugar  is  not  known  to  undergo  any  material 
changes  as  the  result  of  the  condensing  process.  If  condensed  milk 
is  recondensed,  it  assumes  a  darker  color  which  is  largely  due  to 
the  caramelizing  of  a  part  of  the  milk  sugar,  caused  by  the  action 
of  prolonged  exposure  to  heat.  The  milk  sugar  in  condensed  milk 
crystallizes  very  readily  and  causes  the  condensed  milk  to  become 
sandy  and  settled.  Chemical  analyses  of  this  sugar  sediment  show 
that  it  consists  principally  of  milk  sugar.  The  primary  cause  of 
this  property  lies  in  the  fact  that  sweetened  condensed  milk  contains 
so  little  water  (about  26.5  per  cent.)  that  the  milk  sugar  is  present 
in  the  form  of  a  supersaturated  solution ;  therefore,  any  condition 
which  favors  sugar  crystallization  will  tend  to  produce  this  defect.^ 
Milk  sugar  requires  from  five  to  six  times  its  weight  of  water  at 
ordinary  temperatures  for  complete  solution.  In  sweetened  con- 
densed milk  the  milk  sugar  has  access  to  only  about  twice  its  weight 
of  water  (12.5  to  15  per  cent,  lactose  to  25  to  27  per  cent,  water). 

Ash. — The  per  cent,  of  ash  is  largely  dependent  on  the  degree 
of  condensation.  It  usually  varies  from  1.5  to  2  per  cent.  It  is 
quite  constant  in  fresh  milk  (normal  fresh  milk  contains  uniformly 
about  .7  per  cent.  ash).  The  per  cent,  of  ash  in  sweetened  con- 
densed milk  may  serve,  therefore,  as  a  reasonably  reliable  factor  in 
determining  the  degree  of  condensation.  The  heating  of  milk, 
before  condensing,  precipitates  and  renders  insoluble  a  portion  of 
the  mineral  solids,  principally  the  lime  salts. 

Slxrose. — The  purpose  of  the  presence  of  sucrose  in  this 
product  is  to  preserve  it.  Most  of  the  sweetened  condensed  milk 
on  the  market  contains  from  37  to  43  per  cent,  sucrose,  or  cane 
sugar.  Wider  variations,  however,  are  not  infrequent.  In  some 
cases  analyses  showed  as  low  as  30  per  cent,  and  in  others  as  high 
as  48  per  cent,  cane  sugar.  Cane  sugar  dissolves  in  one  half  its 
weight  of  water,  so  that  under  normal  conditions  there  is  sufficient 
water  in  the  condensed  milk  to  keep  the  sucrose  in  solution.     The 


I  For  further  details  on  causes  of  settled  sweetened  condensed  milk  see  Chapter  XXIII, 
page  146 


122  Condensed  Milk  and  Milk  Powder 

amount  of  sucrose  in  milk  does  not  appreciably  atlfect  the  power  of 
the  milk  to  dissolve  milk  sugar,  nor  does  the  per  cent,  of  lactose 
present  materially  affect  the  power  of  the  milk  to  dissolve  sucrose. 
Specific  Gravity. — The  specific  gravity  of  sweetened  con- 
densed milk  falls  within  the  limits  of  1.24  to  1.35.  Foreign  brands 
average  higher  in  specific  gravity  than  American  brands.  The  spe- 
cific gravity  of  sweetened  condensed  milk  is  controlled  by  the  degree 
of  condensation,  the  per  cent,  of  fat  and  the  per  cent,  of  cane  sugar. 
Milk  condensed  at  the  ratio  of  about  2.5  parts  of  fresh  milk  to  i 
part  of  condensed  milk  and  containing  about  9  per  cent,  fat  and  40 
per  cent,  cane  sugar,  has  a  specific  gravity  of  from  1.28  to  1.29.  The 
specific  gravity  of  sweetened  condensed  skim  milk  may  go  as  high 
as  1.35,  and,  if  it  contains  an  excess  of  cane  sugar,  it  may  be  still 
higher. 


Chemical  Analyses  of  Sweetened  Condensed  Milk  of  Eighteen 
Different  Brands 


Brand 

Milk 
solids 

per 
cent. 

Water 
per 
cent. 

Fat 
per 
cent. 

Pro- 
teids 
per 
cent. 

Lac- 
tose 
per 

cent. 

Ash 
per 
cent. 

Sucrose 
per 
cent. 

1  "Silver  Spoon" 
Hires'   Condensed   Milk   Co 

31.90 

28.68 

8.40 

9.12 

12.56 

1.91 

40.38 

3  "Eagle- 

Borden's   Condensed   Milk   Co 

31.08 

25.99 

8.72 

8.15 

12.35 

1.86 

42.93 

2  "Reindeer' 

Truro  Condensed  Milk  Co 

31.23 

27.33 

9.56 

8.32 

13.42 

1  80 

41  44 

3  "Tip  Top" 

Bordens'  Condensed  Milk  Co 

36.57 

21.67 

10.07 

9.35 

15.00 

2.15 

41.76 

3  "Challenge" 

Borden's  Condensed  Milk  Co 

31.7-1 

24.84 

8.23 

8.57 

13.(2 

1.92 

43.42 

3  "Sweet  Clover" 

Mohawk  Condensed  Milk  Co 

32.8-t 

24.07 

9.31 

8.71 

12.95 

1.87 

43.09 

3  "Arrow" 

Wisconsin  Condensed  Milk  Co 

31.15 

26.83 

8.00 

8.49 

12.87 

1.79 

42.02 

3  "Blue  Bell" 

American  Condensed  Milk  Co 

35.56 

26.50 

9.31 

9.50 

14.80 

1.95 

37.94 

3  "Red  Cross" 

Mohawk  Condensed  Milk  Co 

34.78 

27.14 

11.07 

7.92 

14.(:-3 

1.76 

38  56 

3."Rose" 

Borden's  Condensed  Milk  Co 

30.82 

24.76 

8.88 

8.0a 

12.07 

1.81 

42  97 

3  "Magnoha" 

Borden's  Condensed  Milk  Co 

31.98 

26.32 

8  64 

7.84 

13.50 

2.00 

42  00 

3  "Rustic" 

Michigan   Condensed  Milk   Co 

30.00 

27.63 

8.60 

7.07 

12.60 

1.73 

41.00 

2  "Milk  Maid" 

Anglo-Swiss   Condensed   Milk  Co 

35.69 

25.65 

9.65 

8.78 

15.17 

2  09 

38  66 

2  ".Jubilee" 

The  Manitoba  Dairy  Co 

29.40 

32.15 

9.62 

8.61 

11.30 

1.85 

3S.45 

2  "Export" 

Baldwin  Condensed  Milk  Co 

32.24 

26.69 

11.50 

8  50 

12.. 35 

1.80 

41.07 

-  "Owl" 

Canada  Milk  Condensing  Co 

31.61 

30.84 

10.01 

8.47 

12.40 

1.81 

37.-55 

2  "Nestle" 

Henry  Nestle  

.32.91 

28.04 

8.06 

7.68 

15.23 

1.94 

39.05 

3  "Upper  Ten" 

U.  S.   Condensed  Milk  Co 

33.65 

27.88 

8.80 

8.34 

14.66 

1.85 

38  47 

1  Spitzer,  Indiana  Agricultural  E.xperiment  Station,  1910 

2  McGill,  Inland  Rev.  Dept.,  Ottawa,  Bulletin  No.  144,  1908 

3  Cochran,  Special  Report  of  Analysis  of  Condensed  Milks  and  Infants'   Foods,  Penn- 
sylvania Department  of  Agriculture,  1905 


Condensed  Milk  and  Milk  Powder 


123 


Evaporated  Milk. — The  same  factors  which  control  the  chem- 
ical composition  of  sweetened  condensed  milk,  also  govern  that  of 
the  unsweetened  product,  with  the  exception  that  the  cane  sugar  is 
absent. 

The  following  figures  represent,  in  round  numbers,  the  average 
composition  of  evaporated  milk  as  obtained  from  analyses  of  a 
large  number  of  American  brands. 

AVERAGE  COMPOSITION  OF   EVAPORATED  MILK 

Water  73  per  cent, 

fat  8.3  per  cent. 


Milk  solids 


proteids  7.5  per  cent, 
lactose  9.7  per  cent, 
ash  1 .5  per  cent. 


27  per  cent. 


100  per  cent. 

The  chemical  and  physical  properties  of  the  various  ingredients 
in  unsweetened  condensed  milk  are  affected  to  a  greater  extent  than 
in  the  case  of  sweetened  condensed  milk.  This  is  largely  due  to  ex- 
posure of  the  evaporated  milk  to  high  temperatures  in  the  sterilizer. 

Water  and  Solid.s  are  governed  by  the  degree  of  concentration 
and  the  relative  per  cent,  of  the  same  constituents  in  the  fresh  milk. 
The  per  cent,  of  solids  admissible  in  evaporated  milk  is  largely  de- 
pendent on  the  chemical  and  physical  properties  of  the  milk  and  the 
sterilizing  temperatures  employed.  Excess  in  solids  in  this  product 
jeopardizes  its  marketable  properties,  owing  to  the  tendency  of  the 
proteids  to  form  hard  lumps  of  curd  during  the  sterilizing  process. 
Evaporated  milk  very  low  in  solids  tends  toward  the  separation  of 
its  butter  fat  in  storage.  Analyses  show  a  range  of  from  23  to  31 
per  cent,  solids.  Since  the  per  cent,  of  solids  necessary  and  possible 
to  be  contained  in  marketable  evaporated  milk,  largely  depends  on 
the  properties  of  milk,  and,  since  these  properties  again  are  prin- 
cipally controlled  by  locality,  season  of  year,  crop,  feed  and  weather 
conditions  and  the  quality  of  the  fresh  milk,  the  solids  in  milk  from 
any  given  factory  and  at  any  given  season  of  the  year  may  vary 
very  considerably.  In  some  localities  and  at  certain  times  of  the 
year  the  best  results  may  be  obtained  with  evaporated  milk  contain- 
ing 28  per  cent,  solids.     In  other  localities  it  may  be  impossible  at 


124 


Condensed  Milk  and  Milk  Powder 


certain  seasons  of  the  year,  to  incorporate  more  than  24  per  cent, 
sohds  without  injuring  or  destroying  the  marketable  properties  of 
the  product^ 

BuTTERFAT. — The  fat  varies  with  the  per  cent,  of  fat  in  the 
fresh  milk  and  with  the  degree  of  concentration.  No  fat  is  lost  dur- 
ing the  process  of  condensing  and  sterilizing.-  It  has  been  claimed 
by  some  that  in  the  process  of  manufacture,  the  volatile  fatty  acids 
escape  and  that  the  evaporated  milk  therefore  contains  less  fat  than 
the  fresh  milk  from  which  it  is  made,  times  the  degree  of  concen- 
tration. If  this  were  true  the  loss  of  fat  in  the  evaporated  milk 
would  not  exceed  .25  of  i  per  cent.  But  analyses  show  that  the  fat 
in  the  evaporated  milk  is  entirely  normal  in  composition  and  con- 
tains the  same  proportion  of  volatile  fatty  acids  as  the  fat  in  the 
fresh  milk. 


The  Composition  of  Milk  Fats  in  Evaporated 

Milk  - 

Date  ol 
Manufacture 

Eeichert 
Meissl 
number 

Iodine 
number 

Melting  point  of 
mixed  fats 

Melting  point  of 
insoluble 
fatty  acids 

August    1908 

28.48 
29.52 

33.64 
33.60 

33.3  degrees  C. 

33.4  degrees  C. 

41.0  degrees  C 

November    1908 

41  ■'  degrees  C. 

In  the  evaporated  milk  there  is  a  strong  tendency  for  the  fat  to 
separate  out  during  storage  and  to  churn  in  transportation.  This  is 
largely  avoided  by  the  proper  adjustment  of  the  sterilizing  process 
and  by  use  of  the  homogenizer. 

Proteids. — The  proteids  vary  with  the  per  cent,  of  total  pro- 
teids  in  the  fresh  milk  and  the  degree  of  concentration.  Similar  to 
the  case  of  sweetened  condensed  milk  there  is  a  tendency  of  a  slight 
loss  of  proteids  in  evaporated  milk  due  to  mechanical  adhesion  of 
a  part  of  the  precipitated  curd  to  the  heating  surfaces  in  the  fore- 
warmers  and  in  the  vacuum  pan. 

Most  of  the  coagulable  milk  allnimin  is  precipitated.  Fresh 
milk  contains  about  .i6  per  cent,  of  albumin  that  is  not  coagulable 
by  heat.''*  The  relation  of  soluble  and  insoluble  curd  is  shown  in  the 
following  table  which  represents  analyses  of  different  brands  of 
evaporated  milk. 


1  Hunziker,  Indiana  Agricultural  Experiment  Station,  Twenty-first  Annual  Report, 
pages  67-68 

2  Hunziker  and  Spitzer,  Indiana  Agricultural  Experiment  Station,  Bulletin  Xo.  134 

3  Hunkizer,  Indiana  Agricultural  Experiment  Station,  Bulletin  No.  143 


Condensed  Mii,k  and  Milk  Powder 
Soluble  and  Insoluble  Curd  in  Evaporated  Milk 


125 


Brand 

Insoluble 

curd 
per  cent. 

Soluble 
albumin 
per  cent. 

Total 
proteids 
per  cent. 

Gold  Milk 

8.44 
7.41 
7.54 
7.37 
7.86 
8.28 
6.49 
8.39 
7.52 
6.77 
7.06 
6.88 
6.89 
7.21 

.46 
.49 
.46 
.33 
.30 
.34 
.52 
.39 
.42 
.52 
.42 
.52 
.49 
.44 

8.90 

Columbine 

7.90 

8.0 

Gold  Milk 

7.70 

Star 

8.16 

Morning  Glorv 

8.62 

Carnation  

Boautv 

6.91 

8  78 

Van  Camp's 

7.94 

7.29 

Diadem 

7  48 

Reindeer 

7.40 

Wilson's 

7.38 

Dundee 

7  65 

Average 

7.436 

.429 

7.865 

The  above  figures  show  that,  in  the  evaporated  milk,  practically 
all  of  the  coagulable  albumin  is  changed  to  insoluble  curd.  The 
brands  analyzed  contained  evaporated  milk  condensed  at  the  ratio 
of  2  to  2.4  parts  of  fresh  milk  to  i  part  of  evaporated  milk.  The 
soluble  albumin  found  corresponds  with  the  albumin  not  coagulabl© 
by  heat,  normally  found  in  fresh  milk,  times  the  ratio  of  concen- 
tration. 

The  casein  is  largely  precipitated  by  the  sterilizing  heat,  but  is 
present  in  the  form  of  very  finely  divided  particles.  This  is  due  to 
the  mechanical  shaking  to  which  the  evaporated  milk  is  subjected 
in  the  sterilizer  and  in  the  shaker.  In  many  batches  of  evaporated 
milk  the  precipitation  of  the  casein  during  sterilization  is  so  fine 
that  the  product  is  perfectly  smooth  without  shaking.  The  casein 
in  evaporated  milk  does  not  respond  to  the  action  of  rennet  as  does 
the  casein  in  fresh  milk. 

Milk  Sugar. — The  milk  sugar  is  present  in  per  cent,  corre- 
sponding with  that  of  the  original  milk,  times  the  degree  of  con- 
centration. A  portion  of  it  has  undergone  oxidation  (carameliza- 
tion)  due  to  the  high  sterilizing  temperatures.  It  gives  to  the 
evaporated  milk  a  yellow  to  light  brown  color.  The  higher  the 
sterilizing  temperature  and  the  longer  the  exposure  of  the  evaporated 
milk  to  this  heat,  the  darker  is  its  color. 


1  Hunziker,  Indiana  Agripultural  Kxperinient  Station,  Bulletin?  \o.  134  and  143 

-  Hunziker,  Indiana  .Agricultural  Experiment  Station,  Twenty-fifth  Annual  Report,  1908 


126  Condensed  Milk  and  Milk  Powder 

Ash. — The  mineral  constituents  also  are  present  in  nearly  the 
same  proportion  to  the  other  solids,  as  in  fresh  milk.  They  are 
largely  rendered  insoluble  by  the  sterilizing  process.  The  lime  con- 
stituents frequently  are  found  in  the  bottom  of  the  cans  in  the  form 
of  hard,  whitish,  insoluble  granules. 

Since  the  ash  in  normal  fresh  milk  is  practically  constant,  aver- 
aging about  .70  per  cent.,  the  per  cent,  of  ash  in  the  evaporated 
milk  is  frequently  used  as  a  factor  in  determining  the  degree  of  con- 
centration. The  results  may,  however,  be  very  misleading,  since, 
when  the  ash  is  precipitated  in  the  form  of  granules,  it  is  practically 
impossible  to  mix  it  back  into  the  milk  in  order  to  obtain  a  repre- 
sentative sample  for  analysis. 

The  Specific  Gravity  ranges  from  1.05  to  1.08,  according  to 
the  degree  of  concentration  and  the  specific  gravity  of  the  original 
milk.     It  averages  about  1.065. 

Plain  condensed  bulk  milk  is  of  very  varying  composition,  de- 
pending largely  on  the  degree  of  concentration  and  the  per  cent,  of 
fat  present.  It  is  usually  made  from  partly  or  wholly  skimmed 
milk  and  is  condensed  at  the  ratio  of  3  to  4  parts  of  fresh  milk 
to  I  part  of  condensed  milk.  The  same  fact  applies  to  the  com- 
position of  concentrated  milk. 


Condensed  Milk  and  Milk  Powder 


127 


Chemical  Analyses  of  Twenty-four  Different  Brands  of  Evaporated 

Milk^ 


Brand 

Solids 

Water 

Fat 

Curd 

Lactose 

Ash 

Total 

Gold  Milk 

29.25 

70.75 

9.42 

8.44 

9.75 

1.54 

99.90 

Columbine   

24.63 

75.37 

7.45 

7.41 

8.56 

1.36 

99.98 

Every  Day 

26.20 

73.80 

8.07 

7.54 

9.10 

1.47 

100.15 

Gold  Milk 

27.18 

72.82 

9.07 

7.39 

9.23 . 

1.49 

100.00 

Star    

29.04 

70.90 

8.35 

7.86 

10.37 

1.62 

99.16 

Morning  Glory  ___ 

31.08 

68.92 

10.48 

8.26 

10.47 

1.67 

99.82 

Carnation       

23.81 

76.19 

8.05 

6.49 

7.55 

1.24 

99.49 

Beauty       

28.38 

71.62 

8.47 

8.39 

9.94 

1.56 

99.98 

Van  Camp's 

27.89 

72.11 

8.69 

7.52 

9.66 

1.54 

99.52 

Wilson's 

25.23 

74.77 

8.70 

6.53 

8.68 

1.37 

100.05 

Monarch 

26.70 
24.96 

73.30 
75.04 

8.09 
8.16 

6.77 
7.06 

10.35 
7.92 

1.44 
1.33 

99.95 

Diadem     _ 

99.51 

Eeindeer          

26.66 

73.34 

8.08 

6.88 

10.21 

1.45 

99.96 

Dundee 

27.04 

72.96 

8.73 

7.21 

9.36 

1.48 

99.74 

Sundry  samples 

1 

28.02 

71.98 

8.93 

7.68 

9.86 

1.61 

100.06 

2 

31.99 

68.01 

9.68 

8.49 

11.88 

1.69 

99.75 

3 

26.01 

73.99 

8.18 

6.77 

9.24 

1.46 

99.64 

4    -    __ 

27.33 

72.67 

9.04 

6.93 

9.42 

1.51 

99.57 

5 

29.37 

70.63 

9.71 

7.34 

10.52 

1.56 

99.76 

6 

21.12 

78.88 

7.30 

5.78 

6.78 

1.12 

99.86 

7    _  _- 

23.25 

76.75 

7.98 

6.19 

7.96 

1.25 

100.13 

8 

25.48 

74.52 

8.68 

6.34 

8.67 

1.35 

99.56 

9 

26.62 

73.38 

9.20 

7.00 

9.18 

1.37 

100.13 

Spitzer,  Indiana  Agricultural  Experiment  Station,  Bulletin  No.  131,  1909 


CHAPTER  XX 

SANITARY  PURITY  AND  DIETETIC  VALUE  OF 
CONDENSED  MILK 

Sanitary  Purity. — From  the  point  of  view  of  freedom  from 
pathogenic  and  other  harmful  micro-organisms,  all  forms  of  con- 
densed milk  are  superior  to  the  average  market  milk.  In  the  first 
place,  the  manufacture  of  a  marketable  condensed  milk  makes  es- 
sential eternal  vigilance  in  the  control  of  the  quality  of  the  fresh 
milk.  It  is  safe  to  state  that  in  no  milk  plants  does  the  quality  of 
the  fresh  milk  accepted,  receive  as  careful  attention  and  average  as 
high  as  in  the  milk  condensery.  The  foundation  of  the  condensed 
product,  the  fresh  milk,  therefore,  is  of  a  relatively  high  standard 
of  purity. 


128  Condensed  Milk  and  Milk  Powder 

Again,  the  temperature  to  which  the  milk  is  subjected  is  suf- 
ficiently high  to  destroy  the  germs  of  practically  all  milk-borne 
diseases ;  so  that,  unless  the  condensed  milk  becomes  infected  with 
pathogenic  germs  after  condensing  and  before  the  tin  cans  are 
hermetically  sealed,  practically  all  danger  from  disease  germs  is 
eliminated.  In  the  case  of  evaporated  milk  the  marketable  product 
is  free  from  all  forms  of  germ  life.  The  only  exception  to  this  rule 
would  apply  to  concentrated  milk,  in  the  manufacture  of  which  the 
milk  is  not  heated  to  temperatures  detrimental  to  the  life  of  bacteria. 

Dietetic  Value. — The  dietetic  value  of  condensed  miilk  is  largely 
dependent  on  the  effect  of  heated  milk  on  its  nutritive  value  and  on 
digestion.  As  far  as  condensed  milk  is  concerned,  there  are  no 
available  data  that  would  throw  any  light  on  this  subject.  The 
results  of  feeding  experiments  with  heated,  pasteurized,  or  sterilized 
milk  vs.  raw  milk,  however,  may  furnish  a  logical  guide  as  to  the 
dietetic  effect  of  condensed  milk.  Milk  pasteurized  at  high  tem- 
peratures, or  sterilized,  may  be  considered  comparable,  as  far  as  the 
effect  of  heat  is  concerned,  to  condensed  milk. 

Doane  and  Price^  report  the  following  experimental  results : 
"Raw  milk  is  more  easily  digested  when  fed  to  calves  than  either 
pasteurized,  or  cooked  milk.  Contrary  to  theory,  cooked  milk,  when 
fed  to  the  calves  used  in  these  experiments,  caused  violent  scouring 
in  the  majority  of  trials.  A  majority  of  physicians  in  charge  of 
children's  hospitals  corresponded  with,  favored  the  use  of  raw  milk 
for  infants,  when  the  milk  is  known  to  be  in  perfect  condition,  but 
favored  pasteurized  milk  under  ordinary  conditions.  With  one  ex- 
ception all  the  physicians  corresponded  with,  discouraged  the  use  of 
cooked,  or  sterilized  milk  for  infant  feeding." 

Rosenau^  states  that  "Comparative  observations  upon  infants 
under  the  same  conditions  show  that  they  flourish  quite  as  well  upon 
heated  milk  as  upon  raw  milk.  Laboratory  experiments  as  well  as 
chemical  observations  coincide  with  the  view,  that  heated  milk  is 
quite  as  digestible  as  raw  milk.  In  fact  it  is  now  claimed  to  be 
more  so.  Metabolism  experiments  indicate  that  the  utilization  of 
calcium  and  iron  in  the  body  is  more  complete  in  children  fed  upon 
boiled  cow's  milk,  than  in  those  fed  upon  raw  cow's  milk." 


1  Doane  and  Price,  Maryland  Agricultural  Experiment  Station,  Bulletin  No.  77,  IWl 

2  Ro«enau,    United    States    Department    of   Agriculture,    Bureau    of   Animal    Industry, 
Circular  No.  153,  1910 


Condensed  Milk  and  Milk  Powder  129 

Stutzer^  who  conducted  experiments  of  artificial  digestion  re- 
ports in  favor  of  boiled  milk,  while  similar  investigations  made  by 
Ellenberger  and  Hofmeister-  showed  no  difference  in  the  digesti- 
bility between  raw  and  cooked  milk. 

Rodet-'  who  experimented  with  dogs  noticed  a  slight  difference 
in  favor  of  boiled  milk.  Bruning*  fed  dogs,  pigs,  rabbits,  and  guinea 
pigs  with  raw  and  sterilized  milk  and  reports  that  all  results  were 
in  favor  of  the  sterilized  milk.  Bruckler's^  experiments  with  dogs 
showed  that  the  animals  gained  more  in  weight  on  sterilized  milk 
than  on  raw  milk,  but  that  their  general  health,  vigor  and  vitality 
was  better  when  fed  raw  milk.  Variot*'  observed  no  difference  in 
the  effect  on  infants  between  raw  and  boiled  milk. 

Peiper  and  Eichloff  made  post  mortem  examinations  on  num- 
erous dogs  which  had  been  fed  for  prolonged  periods  on  raw  and 
boiled  milk,  respectively.  In  the  dogs  fed  on  boiled  milk  the  marrow 
of  the  bones  was  highly  anaemic,  the  articulation  of  the  bony  struc- 
ture looser,  the  ash  content  of  the  bones  and  the  blood  lower,  and 
there  was  more  sodium  chloride  and  less  fibrin  in  the  blood  than  in 
the  case  of  the  dogs  fed  on  raw  milk. 

Storck'  and  others  attribute  such  infantile  diseases  as  rickets 
and  scurvy  to  the  feeding  of  boiled  milk. 

It  is  generally  assumed  that,  because  the  lime  and  phosphoric 
acid  of  milk  become  largely  insoluble  when  milk  is  heated  to  ster- 
ilizing temperatures,  these  elements  in  sterilized  milk  are  not  suf- 
ficiently available  to  supply  the  needs  of  the  growing  organi.sm.  In 
experiments  with  dogs  Aron  and  Frese^  found  that  the  utilization 
of  the  lime  is  not  affected  by  heating  the  milk  and  that,  as  far  as  the 
assimilation  of  the  lime  by  the  growing  organism  is  concerned,  it  is 
immaterial  in  what  form  the  lime  is  present.  Even  when  fed  in 
difficultly  soluble  form,  as  tertiary  lime  phosphate,  the  lime  was 
utilized  as  well  as  the  lime  of  normal  raw  milk. 

The  fact  that  the  phosphorus  (phosphoric  acid),  needed  for  the 
building  up  of  the  bony  structure,   and  which   is  present   in  milk 


1  Stutzer,  Landw.  Versuchs^Stationen,  40,  p.  307 

2  Ellenberger  &  Hofmeister,  Bericht  ueber  das  Veterinarwesen  Koenigreich  Saohsen,  1890 
»  Rodet,  Coiiipt.  rend.  soc.  biol.,  48,  p.  .5.55 

*  Bruning,  Muenchner  Me<liz..  Wochenschrift.  No.  8,  1905 
*Bruning,  Zeitsehrift  fuer  Tiermed,  10,  p.  110,  1906 
=  Bnickler.  Jahrbuch  fuer  Kinderheilk.  66,  p.  343,  1907 
«  Variot,  Comp.  rend.,  139,  p.  1002,  1904 

"  Storck,  zit.   n.   Kmisel,    Studien   ueber  die  sog.   sterilisierte   Milch  des  Handels.   Diss., 
Luzern,  1908 

s  ATon  and  Frese,  Grimmer  Chemie  u.  Phy.«iologie  der  Milch,  1910 


130  Condensed  Milk  and  Milk  Powder 

largely  in  organic  combination  as  casein  and  as  lecithin,  is  changed 
by  heat  to  inorganic  combinations,  the  lecithin  phosphorus  by 
saponification,  and  the  casein  phosphorus  by  changes  in  the  casein 
molecule,  'suggests  a  poorer  retention  of  the  inorganic  phosphorus 
by  the  animal  body.  Cronheim  and  Mueller^  who  studied  this  phase 
of  nutrition  could  detect  no  appreciable  difference  as  to  the  assim- 
ilation of  phosphorus  by  feeding  sterilized  and  raw  milk,  respec- 
tively.    Their  results  were  rather  in  favor  of  sterilized  milk. 

Grimmer-  holds  that  digestive  and  intestinal  disorders  in  infants 
are  possibly  largely  due  to  biological  disturbances,  modifying  the 
bacterial  flora  of  the  intestines,  and  to  the  absence  of  lecithin  and 
unorganized  ferments  in  heated  milk.  He  reports  that  the  addition 
to  boiled  milk  of  substances  rich  in  lecithin,  such  as  the  yolk  of  egg, 
also  ferments,  such  as  pepsin,  trypsin,  and  emulsin  produce  a  marked 
improvement  in  such  cases. 

The  foregoing  citations  suggest  that  our  knowledge  of  the 
dietetic  effect  of  heated  or  boiled  milk  is  exceedingly  limited  and 
that  the  results  obtained  and  conclusions  drawn  by  the  various  in- 
vestigators are  at  variance.  In  experiments  with  the  living  organ- 
ism, and  confined  to  so  few  specimen  as  seems  to  have  been  the  case 
in  the  work  reported,  the  factors  of  individuality  and  environment 
are  a  constant  stumbling  block,  magnifying  the  limit  of  experimental 
error  and  weakening  the  conclusiveness  of  the  results.  On  the  basis 
of  our  present  knowledge  it  seems  reasonable  to  conclude  that,  as 
far  as  the  digestibility  of  its  inherent  ingredients  is  concerned,  con- 
densed milk,  when  consumed  in  properly  diluted  form,  varies  but 
little,  if, any,  from  raw  milk.  The  absence  in  condensed  milk  of 
ferments,  such  as  enzymes,  which  are  destroyed  in  the  process  and 
which  may  assist  digestion,  may  be  considered  the  most  important 
defect  of  condensed  milk  from  the  dietetic  point  of  view. 

In  the  case  of  sweetened  condensed  milk,  however,  the  nutritive 
ratio  of  the  normal  milk  is  decisively  disturbed  by  the  presence  of 
large  quantities  of  sucrose.  Even  when  diluted  to  far  beyond  the 
composition  of  normal  and  original  fluid  milk,  the  per  cent,  of  cane 
sugar  is  still  high,  causing  the  nutritive  ratio  of  such  milk  to  be 
abnormally  wide  and  unbalanced.  The  carlx)hydrates  are  present 
far  in  excess  of  the  protein,  fat  and  ash.     If  fed  to  infants  exclu- 


^  Cronheim  and  Mueller,  Jahrbuch  fuer  Kinderheilk,  57,  p.  4r),  1903 
-  Grimmer,  Chemie  and  Physiologic  der  Milch,  1910 


Condensed  Milk  and  Milk  Powder  131 

sively  and  for  a  prolonged  period  of  time,  the  growing  organism  is 
bound  to  suffer  from  malnutrition  and  at  the  expense  of  muscular 
development. 

Furthermore,  it  is  conceded  by  the  medical  profession  that 
sucrose  is  not  a  suitable  form  of  carbohydrates  for  infants.  It  is 
not  as  digestible  as  lactose,  it  changes  the  bacterial  flora  of  the 
intestines,  enhancing  the  development  of  butyric  acid  and  other  gas 
forming  and  putrefactive  germs  at  the  expense  of  Bacillus  bifidus, 
which  is  the  natural  inhabitant  of  the  intestine  in  normal,  milk- 
fed  babies. 

Sweetened  condensed  milk  is  generally  highly  advertised  by  the 
manufacturer  as  a  suitable  food  for  babies;  it  is  frequently  recom- 
mended by  physicians  and  in  some  instances,  it  is  claimed  to  have 
agreed  with  babies  who  were  unable  to  take  care  of  milk  in  any 
other  form.  It  is  not  improbable  that  in  these  extremely  isolated 
cases  of  baby  feeding,  when  all  other  feeds  failed,  the  true  virtue 
attributed  to  the  sweetened  condensed  milk,  lay  in  the  fact  that  the 
mothers  carefully  followed  the  directions  on  the  label  for  dilution. 
The  directions  specify  that  the  condensed  milk  be  diluted  with  ten 
to  sixteen  parts  of  water.  The  majority  of  cases  of  digestive  dis- 
orders in  bottle-fed  babies  are  undoubtedly  the  result  of  the  natural 
tendency  of  the  mother  to  feed  her  child  too  much  milk  or  too  rich 
milk.  When  we  consider  that  the  ratio  of  concentration  in  sweet- 
ened condensed  milk  is  only  about  2.5  to  i,  it  is  obvious  that  a 
dilution  of  10  or  16  to  i  is  a  great  relief  to  the  over-taxed  digestive 
organs  of  infants,  previously  fed  on  milk  too  rich  for  normal  diges- 
tion. The  immediate  change  of  the  health  and  disposition  of  these 
babies  for  the  better,  as  the  result  of  turning  from  a  prolonged  siege 
of  too  rich  food  to  the  very  dilute  condensed  milk,  is  therefore  not 
surprising. 

The  rnanufacturer  of  sweetened  condensed  milk  in  this  country 
is  inclined  to  load  his  product  excessively  j^vith  sucrose.  He  does 
this  largely  in  an  effort  to  increase  the  keeping  quality  and  to  guard 
against  the  development  of  fermentations  in  the  finished  article  that 
ruin  the  goods  for  the  market.  While  a  certain  amount  of  sucrose 
is  necessary  to  preserve  this  milk,  yet,  if  the  product  is  manufactured 
from  a  good  quality  of  fresh  milk,  as  it  should  be,  and  when  the 
proper  sanitary  conditions  are  maintained  in  all  departments  of  the 


132  Condensed  Milk  and  Milk  Powder 

factory,  sixteen  pounds  of  cane  sugar  per  one  hundred  pounds  of 
fresh  milk  is  entirely  sufficient.  He  should  bear  in  mind  that  sweet- 
ened condensed  milk  is  used  and  accepted  by  the  consumer  as  a 
substitute  for  market  milk,  and  it  is  the  manufacturer's  moral  duty 
to  retain  in  this  substitute  the  normal  properties  and  composition 
of  the  product  which  it  is  supposed  to  replace,  as  nearly  as  is  con- 
sistent with  the  production  of  a  wholesome  and  marketable  product. 


CHAPTER  XXI 
CONDENSED  MILK  STANDARDS  AND  LAWS 

The  Federal  Food  and  Drugs  Act,  passed  June,  1906,  and  which 
went  in  force  January  i,  1907,  has  raised  the  standard  of  excellence 
of  condensed  milk  to  no  small  degree.  It  has  served  as  a  purifier 
of  the  entire  industry,  putting  a  premium  on  the  product  of  the 
honest  manufacturer  and  insuring  the  public  against  condensed  milk 
of  inferior  food  value. 

Prior  to  the  enforcement  of  this  act,  three  states  only  had 
definite  standards  and  laws  regulating  the  composition  of  condensed 
milk.  In  the  absence  of  a  federal  law,  car  loads  of  condensed  skim 
milk  were  unloaded  and  sold  as  condensed  milk  in  states  and  cities 
which  had  no  laws  or  ordinances  prohibiting  the  sale  of  condensed 
skim  milk,  labeled  condensed  milk.  The  Federal  Food  and  Drugs 
Act,  executed  through  the  offices  of  the  Interstate  Commerce  De- 
partment, put  a  stop  to  this  fraud,  protecting  the  public  from  these 
inferior  goods,  eliminating  the  manufacture,  traffic  and  competition 
of  an  unlawful  product,  enhancing  the  business  of  legitimate  manu- 
facture and  raising  the  standard  and  integrity  of  the  industry. 

Federal  Standards.^ — The  Federal  Standards  for  sweetened 
condensed  milk  and  evaporated  milk  which  went  into  force  January 
I,  1907,  are  as  follows; 

"SwEETENE^D  Condensed  Milk  is  milk  from  which  a  consider- 
able portion  of  water  has  been  evaporated  and  to  which  sugar 
(sucrose)  has  been  added  and  contains  not  less  than  28  (twenty- 
eight)  per  cent,  of  milk  solids,  of  which  not  less  than  27.5  (twenty- 
seven  and  five-tenths)  per  cent,  is  milk  fat." 

1  Unitwl  States  Department  of  Agrriciilture,  Circular  No.  19;   also  Indiana  Agricultural 
Experiment  Station  Bulletin  No.  143 


Condensed  Milk  and  Milk  Powder  133 

This  standard  is  reasonable,  just,  adequate  and  attainable  under 
all  normal  conditions.  Sweetened  condensed  milk  in  hermetically- 
sealed  tin  cans  averages  about  32  per  cent,  milk  solids,  and  the  per 
cent,  of  milk  solids  can  be  increased  considerably  above  this  aver- 
age without  injuring  the  marketable  properties  of  the  product. 
Manufacturers  of  sweetened  condensed  milk  well  know  from  costly 
experience,  that  it  would  not  do  to  drop  the  per  cent,  of  milk  solids 
to  or  below  28  per  cent.  Such  milk  would  be  too  thin  to  hold  the 
sugar  in  suspension,  the  sugar  would  tend  to  settle  to  the  bottom  of 
the  cans,  rendering  the  product  unsalable,  though  not  necessarily 
unwholesome.  Again,  this  thin  milk  does  not  keep  well,  it  is  prone 
to  undergo  fermentation.  The  manufacture  of  a  good  quality  of 
salable  sweetened  condensed  milk  requires  that  the  fresh  milk  be 
condensed  at  the  ratio  of  about  2^  :i.  With  this  ratio  of  concen- 
tration it  is  obvious  that  it  is  not  difficult  to  incorporate  28  per  cent., 
or  over,  of  milk  solids  in  sweetened  condensed  milk  at  all  times. 

"Evaporated  Milk  is  milk  from  which  a  considerable  portion 
of  water  has  been  evaporated  and  contains  not  less  than  28  (twenty- 
eight )  per  cent,  milk  solids,  of  which  not  less  than  27.5  (twenty- 
seven  and  five-tenths)  per  cent,  is  milk  fat." 

Unfortunately,  for  the  moral  effect  of  the  law  and  for  the 
progress  of  the  condensing  industry,  the  standard  of  evaporated 
milk  w^as  made  so  high,  evaporated  milk  shall  contain  28  per  cent, 
solids,  that  it  was  found  to  be  beyond  the  reach  of  the  manufacturer 
to  comply  with  it  under  most  conditions  without  impairing  the  mar- 
ketable properties  of  the  product.  The  results  of  this  error  have 
confronted  many  an  honest  manufacturer  with  unsurmountable  dif- 
ficulties. He  was  compelled  to  choose  between  two  equally  unsat- 
isfactory alternatives,  i.  e.,  either  to  manufacture  a  product  below 
standard,  violating  the  law,  or  to  close  his  factory. 

Modified  Evaporated  Milk  Standard. — The  unreasonableness 
of  the  Federal  Standard  for  evaporated  milk  was  experimentally 
demonstrated  by  results  of  investigations  conducted  at  the  Indiana 
Agricultural  Experiment  Station.^  Further  extensive  investigations 
were  made  by  the  United  States  Bureau  of  Chemistry.-  Finally, 
in  March,  1911,^  the  standard  was  modified  to  read  as  follows: 


1  Hunziker,  Indiana  Agricultural  Experiment  Station  Bulletin  Xo.  ]43,  1910 

2  Results  not  published 

3  United  States  Department  of  Agriculture,  Food  Inspection  Decifi  n  Xo.  131,  1911 


134  Condensed  Milk  and  Milk  Powder 

"i.  Evaporated  milk  should  be  prepared  by  evaporating  fresh, 
pure  whole  milk  of  healthy  cows,  obtained  by  complete  milking  and 
excluding  all  milkings  within  fifteen  days  before  calving  and  seven 
days  after  calving,  provided  that  at  the  end  of  this  seven  day  period 
the  animals  are  in  a  perfectly'  normal  condition. 

"2.  It  should  contain  such  percentages  of  total  solids  and  of 
fat  that  the  sum  of  the  two  shall  be  not  less  than  34.3  and  the 
percentage  of  fat  shall  be  not  less  than  7.8  per  cent. 

"3.  It  should  contain  no  added  butter  or  butter  oil  incor- 
porated either  with  whole  milk  or  skimmed  milk  or  with  the  evap- 
orated milk  at  any  stage  of  manufacture." 

This  modified  standard  was  an  improvement  over  the  original 
standard  which  it  superseded.  However,  the  requirements  of  solids 
were  still  too  high. 

Difficulties  of  Meeting  These  Standards  for  Evaporated  Milk. 
— While  these  standards  can  be  complied  with  in  some  localities  and 
under  certain  favorable  conditions,  they  are  beyond  the  reach  of 
the  manufacturer  in  other  localities  and  under  less  favorable  con- 
ditions. The  manufacturer  is  compelled,  in  order  to  produce  a 
marketable  product,  to  use  sufficiently  high  temperatures  in  the 
sterilizer  to  render  the  milk  absolutely  sterile.  This  he  must  ac- 
complish without  causing  the  product  to  become  curdy. 

The  degree  of  concentration  of  the  evaporated  milk  directly 
controls  its  curdling  properties.  The  higher  the  degree  of  concen- 
tration, the  greater  is  the  danger  of  a  curdy  product.  Unfortunately, 
the  agents  which  regulate  the  ease  with  which  milk  curdles,  are  not 
under  the  control  of  the  operator.  They  have  to  do  with  breed, 
period  of  lactation,  condition,  care  and  feed  of  the  cows,  season 
of  year,  climatic  and  weather  conditions  and  the  care  and  chemical, 
physical  and  physiological  properties  of  the  milk  on  the  farm.  It 
so  happens  that  in  localities,  where  dairying  has  not  as  yet  reached 
a  high  state  of  development,  where  cows  are  exposed  to  inclement 
weather,  or  in  the  southern  tier  of  the  dairy  belt,  where  the  cows 
sufifer  from  the  sweltering  heat  of  the  summer  months  and  are 
pestered  with  flies,  and  where  the  available  water  for  cooling  the 
milk  on  the  farm  is  not  very  cold,  the  milk  is  more  prone  to  curdle, 
than  in  highly  developed  dairy  countries,  or  in  localities  of  the  cooler 
regions  of  the  dairy  belt,  etc. 

The  properties  of  milk  to  curdle,  whatever  the  agents  causing 
them  may  be,  are  intensified  by  the  degree  of  concentration.     It  is. 


Condensed  Milk  and  Milk  Powder  135 

therefore,  necessary  for  the  successful  manufacture  of  a  salable 
product  to  regulate  this. 

A  further  objection  to  both,  the  original  and  the  modified 
standard  for  evaporated  milk  is  that,  where  milk  is  bought  and 
paid  for  on  the  basis  of  butterfat  contained  therein,  as  it  should  be, 
the  factory  receiving  high-testing  milk,  labors  financially  under  a 
distinct  disadvantage.  The  reason  for  this  is  that  in  high-testing 
milk,  such  as  Jersey  and  Guernsey  milk,  the  butterfat  constitutes 
about  34  per  cent,  of  the  total  solids,  while  in  low-testing  milk,  such 
as  Holstein  milk,  the  butterfat  constitutes  only  about  28  per  cent. 
of  the  total  solids.  In  order  to  meet  the  requirements  for  milk 
solids,  more  butterfat  has  to  be  put  into  the  evaporated  milk  per 
case,  where  high-testing  milk  is  condensed  than  in  the  case  of  low- 
testing  milk.  Consequently,  the  cost  per  case,  of  the  manufacture 
of  such  milk  is  greater  than  that  of  low-testing  milk.  These  stand- 
ards, therefore,  discriminate  in  favor  of  manufacturers  and  breeds 
of  low-testing  milk,  such  as  milk  from  Holsteins  and  Ayrshires,  and 
against  manufacturers  and  breeds  of  high-testing  milk,  such  as  milk 
from  Jerseys  and  Guernseys. 

Putting  the  Composition  of  the  Evaporated  Milk  011  the  Label. 
— As  the  result  of  these  difficulties,  numerous  manufacturers  pro- 
tested against  these  standards  and  succeeded  in  obtaining  from  the 
Government  temporary  concessions  to  the  effect  that  "there  would 
be  no  violation  of  the  Food  and  Drugs  Act  if  the  percentage  com- 
position of  the  goods  was  plainly  stated  on  the  label  in  connection 
with  the  name  of  the  substance,  although  this  might  be  lower  than 
that  required  by  Food  Inspection  Decision  No.  131."  This  informa- 
tion was  issued  by  the  Government  to  the  condenseries  in  the  form 
of  a  circular  letter. 

As  the  result  of  this  concession,  many  condenseries,  which  ex- 
perienced difficulties  in  complying  with  the  original  standard, 
adopted  individual  standards  of  composition  in  accordance  with 
their  local  conditions  and  they  stated  on  the  label,  in  more  or  less 
legible  type,  the  percentages  of  solids  and  fat  below  which  their 
goods  would  not  drop. 

Subsequent  investigations  by  the  Government,  however,  seemed 
to  indicate  that  this  form  of  labeling  was  misleading  to  the  public 
and  would,  therefore,  be  in  violation  of  the  Food  and  Drugs  Act. 


136  Condensed  Milk  and  Milk  Powder 

Consequently,  the  concession  of  permitting  individual  standards  was 
then  withdrawn. 

The  Federal  Board  of  Food  Inspection  is  further  considering 
the  advisability  of  modifying  the  evaporated  milk  standard,  but 
until  a  decision  is  reached,  the  standard  proclaimed  in  Food  In- 
spection Decision  No.  131  is  valid. 

Condensed  Skim  Milk. — The  Federal  Standard  for  condensed 
skim  milk  is  as  follows : 

"Condensed  skim  milk  is  skim  milk  from  which  a  considerable 
portion  of  water  has  been  evaporated." 

To  this  class  of  condensed  milk  belongs  all  condensed  milk 
made  from  wholly  or  partly  skimmed  milk. 

CHAPTER  XXII 
COST  OF  MANUFACTURE 

General  Discussion. — The  cost  of  manufacture  varies,  in  a  gen- 
eral way,  with  the  organization  and  size  of  the  factory,  capacity  of 
machinery  and  the  amount  of  the  output.  These  variations  are 
further  modified  by  the  cost  of  available  labor,  the  price  of  milk, 
cane  sugar,  tin  cans,  box  shooks,  coal  and  other  supplies,  etc. 

In  a  properly  organized  plant  the  cost  of  manufacture  per  case 
of  finished  product  decreases  with  the  increase  of  the  output,  pro- 
vided that  the  capacity  of  the  machinery  is  sufficient  to  take  care  of 
such  increase.  When  the  plant  is  forced  beyond  its  capacity,  the 
factory  operates  at  a  disadvantage,  and  the  extra  labor  and  possible 
waste  and  losses  tend  to  increase  the  cost  per  case.  When  the 
output  drops  below  100  to  150  cases  per  day,  profitable  manufacture 
becomes  difficult,  the  overhead  expense  is  out  of  proportion  with 
the  business,  the  factory  cannot  take  advantage  of  rebates  in  the 
purchase  of  supplies,  the  factory  labor  is  relatively  high,  because 
skilled  men  have  to  do  manual  labor,  and  occasional  losses  due  to 
spoiled  goods  devour  the  profits  of  a  comparatively  large  portion  of 
the  entire  output. 

The  price  of  milk  fluctuates  with  season  and  proximity  and 
strength  of  competing  markets.  The  fluctuations  embrace  a  range 
of  from  $1.00  to  $2.00  per  one  hundred  pounds  of  fluid  milk,  or 
twenty-five  cents  to  fifty  cents  per  pound  of  butter  fat. 


Condensed  Milk  and  Milk  Powder  137 

Cane  sugar  varies  in  price  largely  with  the  season  and  with  the 
success  or  failure  of  the  sugar  cane  crop.  Sugar  prices  usually  reach 
their  climax  in  fall  and  their  minimum  price  in  late  winter  or  early 
spring.  The  variations  usually  fall  within  the  limits  of  $4.00  and 
$6.50  per  one  hundred  pounds  of  sugar. 

Tin  cans  vary  in  price  with  style  of  can  and  whether  made  in 
the  condensery  or  bought  from  a  can-making  concern.  Some  fac- 
tories are  paying  more  or  less  heavy  royalties  for  the  privilege  of 
using  certain  patents  of  cans.  Cans  intended  to  be  sealed  without 
the  use  of  solder,  but  which  are  guaranteed  to  make  a  hermetical 
seal,  are  generally  higher- in  price  than  those  in  the  sealing  of  which 
solder  is  used.  This  difference  in  price,  however,  is  oft"set,  in  part 
at  least,  by  the  cost  of  the  solder  and  gasoline.  Cans  purchased 
from  can-making  concerns  usually  are  more  expensive  than  cans 
manufactured  in  the  condensery.  This  holds  true  only  where  the 
tin-shop  of  the  condensery  is  properly  equipped  and  efficiently 
manned.  The  cost  of  cans  bought  from  can-making  concerns  is 
about  fifty-five  cents  per  case,  varying  somewhat  with  size  and  style 
of  can ;  when  made  in  the  condensery  the  price  may  be  lowered  from 
10  to  20  per  cent. 

The  cost  of  coal  varies  with  quality  and  locality.  Under  aver- 
age conditions,  the  condensing  and  packing  of  one  pound  of  fluid 
milk  requires  about  three-tenths  of  a  pound  of  coal  or  thirty  to 
forty  pounds  per  case.  A  good  quality  of  "mine  run"  can  be  laid 
down  at  the  factory  in  states  near  the  coal  region,  like  Indiana  and 
Illinois  for  about  $2.50  per  ton,  or  in  northern  states,  like  Wisconsin, 
for  about  $3.30  per  ton.  The  cost  of  coal  per  case,  therefore,  may 
vary  from  about  three  and  eight-tenths  cents  to  six  and  a  half  cents 
per  case.  Where  natural  gas  or  refuse  from  lumber  mills  are  avail- 
able, the  cost  of  fuel  may  be  reduced  materially  by  the  use  of  these 
substitutes  for  coal. 

Solder  and  gasoline  for  sealing  the  cans  average  about  three 
and  a  half  cents  per  case.  The  price  of  solder  is  about  twenty-seven 
cents  per  pound  and  the  solder  used  per  case  of  forty-eight  cans 
amounts  to  about  one-tenth  of  a  pound. 

The  labels  vary  in  price  according  to  quality  of  paper,  and 
elaborateness  of  printing.  The  average  cost  of  labels  is  about  four 
cents  per  case. 


138  Condensed  Milk  and  Milk  Powder 

The  box  shocks  and  nails  per  case  cost  about  eight  to  ten  cents. 

The  labor,  including  factory  labor,  the  office  personnel  and  the 
manager's  salary  is  about  twenty-five  cents  per  case,  varying  ob- 
viously with  the  organization  and  output  of  the  factory. 

The  interest  on  the  investment  and  insurance  amount  to  about 
two  and  a  half  to  three  cents  per  case.  A  factory  manufacturing 
two  hundred  cases  of  condensed  milk  per  day  requires  an  invest- 
ment of  about  $25,000  for  building  and  equipment  and  about  $10,000 
for  operating  capital. 

The  expense  of  freight  and  other  transportation  ranges  from 
about  five  to  twenty  cents  per  case,  according  to  distance.  It  may 
average  about  twelve  cents  per  case. 

The  selling  expense  varies  considerably  with  the  organization 
of  the  sales  department  and  the  type  and  extent  of  advertising  done. 
Under  favorable  conditions  it  may  be  held  down  to  twenty-five  to 
thirty  cents  per  case.  If  premiums  are  awarded  the  cost  is  about 
ten  cents  extra.  The  introduction  of  new  brands  often  incurs  an 
expense  as  high  as  $1.00  per  case.  The  average  sales  expense  may 
be  consistently  placed  at  thirty  to  forty  cents  per  case. 

For  convenience  sake  the  cost  per  case  may  be  grouped  as 
follows : 


Condensed  Milk  and  Milk  Powder 


139 


SWEETENED  CONDENSED    MILK 

Cost  per  Case  of  Forty-eight  Cans  Containing  About  Forty  Pounds 
of  Condensed  Milk 


100  pounds  milk  @  $1.50 

16  pounds  cane  sugar  @  $5.00  per  100  pounds. 

Cans 

Boxes  @  $7.40  per  100 

Labels 

Solder  and  gasoline 

Coal    

Labor   

Interest  on  investment  and  insurance 

Freight  

Selling   expense    


.$1.50 
,   .90 
45 
075 
04 

035 

045 

25 

03 

12 

35 


Total  cost  of  manufacture  and  sale  of  one  case  of 

sweetened  condensed  milk   $3-795 


EVAPORATED   MILK 


Cost  per  Case  of  Forty-eight  Tall-size  Cans  Containing  Fifty-four 
Pounds  of  Evaporated  Milk 


no  pounds  milk  @  $1.50  per  hundred  pounds $1 

Cans   

Boxes   

Labels 

Solder  and  gasoline 

Coal    

Labor   

Interest  on  investment  and  insurance 

Freight   

Selling   expense    


65 
55 
075 
04 

035 

045 

25 

03 

12 

35 


Total  cost  of  manufacture  and  sale  of  one  case  of 

tall-size  cans  of  evaporated  milk $3-i45 


Condensed  Milk  and  Milk  Powder  141 


PART    VI 

CONDENSED  MILK  DEFECTS,  THEIR  CAUSES 
AND  PREVENTIONS 

CHAPTER  XXIII 

CLASSIFICATION  OF  DEFECTS 

If  we  recognize  in  fresh  cow's  milk  an  article  of  food,  highly- 
complex  in  composition,  subject  to  many  and  complex  changes  and 
to  rapid  deterioration  unless  handled  carefully  and  skillfully,  then 
the  successful  manufacture  of  condensed  milk,  a  product  more  com- 
plex in  its  composition  and  exposed  to  more  diverse,  more  vary- 
ing and,  in  most  cases,  more  unfavorable  conditions  than  fresh 
milk,  must  involve  a  knowledge  that  extends  beyond  the  mere 
mechanical  knack  of  heating,  adding  sugar,  evaporating,  sterilizing, 
cooling,  filling,  sealing  and  packing. 

The  simplicity  of  the  process  tends  to  belittle  and  hide  the 
complexity  of  the  product.  Anybody  can  acquire  the  routine  knowl- 
edge of  condensing  milk,  but  few  can  make  a  uniformly  good  quality 
of  condensed  milk.  It,  therefore,  happens  that  defective  condensed 
milk  is  made  now  and  then  in  most,  if  not  all  condenser ies,  and  that 
the  output  of  a  poor  quality  of  condensed  milk  is  not  necessarily 
the  exception,  but  quite  often  the  rule. 

Many  are  the  defects  which  cause  condensed  milk  to  be  re- 
jected on  the  market  and  numerous  are  the  avenues  that  may  lead 
to  the  manufacture  of  defective  milk.  The  milk  faults  may  be  of 
mechanical,  physical,  chemical,  or  bacteriological  origin,  or  they  may 
be  due  to  a  combination  of  two  or  more  of  these  forces.  In  some 
instances  the  defects  can  be  detected  in  milk  during,  or  immediately 
after  the  process,  in  which  case  they  may  be  remedied,  or  their  re- 
currence prevented.  But  more  often,  several  weeks  may  pass  before 
abnormalities  develop  and  before  the  manufacturer  realizes  that 
something  is  wrong  with  the  milk.  In  the  meantime,  the  conditions 
which  originally  produced  the  milk  defect  may  have  so  changed,  that 
it  is -exceedingly  difiicult  to  locate  the  seat  of  the  original  trouble. 


142  Condensed  Milk  and  Milk  Powder 

DEFECTIVE  SWEETENED  CONDENSED  MILK 

The  following  are  the  chief  and  most  common  defects  of 
sweetened  condensed  milk: 

1.  Sandy,  rough  or  gritty 

2.  Settled 

3.  Thickened  and  cheesy 

4.  Lumpy,  white  or  yellow  buttons 

5.  Blown  or  fermented 

6.  Rancid 

7.  Putrid 

8.  Brown 

Sandy,  Rough  or  Gritty  Sweetened  Condensed  Milk 

General  Description. — ^This  is  condensed  milk  in  which  a 
portion  of  the  milk  sugar  has  been  precipitated  in  the  form  of 
crystals,  the  size  of  the  crystals  depending  on  the  conditions  causing 
crystallization.  First-class  sweetened  condensed  milk  is  smooth  and 
velvety.  Such  milk  is  not  entirely  free  from  sugar  crystals,  but 
they  are  so  minute  in  size  that  they  do  not  rob  the  condensed  milk 
of  its  natural  smoothness.  In  sandy  or  gritty  condensed  milk  the 
crystals  are  very  numerous  and  large  enough  to  grind  between  the 
teeth,  similar  to  salt  crystals  in  gritty  butter.  The  presence  of  these 
crystals  is  also  noticeable  to  the  naked  eye;  the  milk  looks  candied. 

Causes  and  Prevention. — ^The  sugar  crystals  which  render 
the  condensed  milk  rough  and  sandy  consist  largely  of  milk  sugar. 
The  solubility  of  milk  sugar  is  relatively  low.  Milk  sugar  requires 
about  six  times  its  weight  of  water  at  ordinary  temperature  for 
complete  solution.  Condensed  milk  contains  from  12.5  to  15  per 
cent,  milk  sugar  and  only  about  26.5  per  cent  water.  The  ratio  of 
milk  sugar  to  water  in  sweetened  condensed  milk,  therefore,  is  i  :2, 
while  for  complete  solution  it  should  be  i  :6.  The  milk  sugar  in  this 
product  is  present  in  a  supersaturated  solution  and  any  condition 
which  favors  sugar  crystallization  strongly  tends  to  precipitate  this 
milk  sugar,  because  there  is  more  of  it  present  in  the  milk  than  the 
available  water  is  capable  of  readily  keeping  in  solution.  The  chief 
factor  that  prevents  the  milk  sugar  from  precipitating  very  badly 
is  the  great  viscosity  of  the  condensed  milk.  This  is  largely  due  to 
the  caseous  matter  and  the  cane  sugar. 


CoNDEN'^KD  Milk  and  Milk  Powder  143 

Cane  Sugar  Content. — It  has  been  argued  that  the  large  amount 
of  sucrose  which  sweetened  condensed  milk  contains,  is  the  principal 
cause  of  sandy  milk  and  of  sugar  sediment  in  the  bottom  of  the  tin 
cans,  and  that  a  reduction  in  the  amount  of  sucrose  lessens  the 
tendency  of  the  sugar  to  crystallize  and  the  milk  to  become  sandy. 
This  line  of  reasoning  is  erroneous.  The  presence,  in  water,  of 
sucrose  in  solution  does  not  materially  lessen  the  power  of  the 
water  to  dissolve  milk  sugar,  provided  that  the  sucrose  solution  is 
not  a  saturated  one.  Sweetened  condensed  milk,  contains  about  35 
to  45  per  cent,  sucrose  and  24  to  28  per  cent,  water.  Sucrose  dis- 
solves in  one  half  its  weight  of  water.  The  sweetened  condensed 
milk  does  not,  therefore,  contain  a  saturated  solution  of  sucrose. 

The  chief  factors  causing  milk  sugar  crystallization  and  sandy 
condensed  milk  are:  incomplete  solution  of  the  sucrose,  excessive 
chilling  in  the  vacuum  pan,  superheating  in  the  vacuum  pan,  im- 
proper cooling,  excessive  stirring,  and  warming  up  too  coid  con- 
densed milk  with  the  help  of  agitation. 

Incomplete  Solution  of  Sucrose. — If  the  finished  product  is  to 
be  smooth  and  free  from  sandiness,  it  is  essential  that  the  sucrose 
which  is  added  to  the  hot,  fresh  milk  be  thoroughly  dissolved  before 
the  mixture  reaches  the  vacuum  pan.  Undissolved  sugar  crystals 
in  a  medium  as  highly  concentrated  as  sweetened  condensed  milk 
have  much  the  same  effect  in  a  physical  way,  as  have  bacteria  in 
fresh  milk  in  a  biological  way;  they  multiply  rapidly.  Therefore, 
if  all  the  sugar  added  to  the  fluid  milk  is  not  completely  dissolved, 
the  undissolved  sugar  crystals  give  rise  to  wholesale  precipitation  of 
the  milk  sugar  in  this  product  after  manufacture.  Complete  solu- 
tion of  the  cane  sugar  can  best  be  accomplished  by  heating  the 
liquid,  milk  or  water,  in  which  the  sugar  is  to  be  dissolved,  to  the 
boiling  point  and  by  boiling  the  mixture  for  several  minutes ;  or  by 
placing  the  sugar  on  a  large  wire  mesh  strainer  (about  eighty 
meshes  to  the  inch)  which  stretches  across  the  sugar  well  and 
allows  hot  milk  to  run  over  this  sugar  into  the  well  below.  In  this 
way  the  sugar  crystals  must  dissolve  before  they  can  reach  the 
sugar  well. 

One  of  the  safest  methods  of  insuring  complete  solution  of  the 
cane  sugar  is  to  dissolve  it  in  a  separate  kettle  in  a  sufficient  quan- 
tity of  boiling  water  (preferably  distilled  water)  and  boiling  the 
syrup  for  five  to  fifteen  minutes.     If  the  syrup  thus  made  is  given 


144  Condensed  Milk  and  Milk  Powder 

a  few  minutes  rest  it  should  become  perfectly  clear ;  by  its  clearness, 
the  purity  of  the  sugar  can  also  be  observed.  If  a  scum  forms  at 
the  top  it  should  be  removed ;  then  the  hot  sugar  syrup  is  drawn 
into  the  pan.  Care  should  be  taken  that  the  milk  already  condensing 
in  the  pan  has  not  become  too  concentrated,  otherwise  sugar 
crystallization  may  set  in.  It  is  advisable  to  inject  the  sugar  syrup 
gradually,  rather  than  to  wait  until  nearly  all  the  milk  is  in  the  pan. 

Excessive  Chilling  in  the  Pan. — The  cause  of  grittiness  of  con- 
densed milk  may  lie  in  the  pan  itself.  Where  the  water  used  for 
condensing  is  very  cold,  and  where  one  end  of  the  spray  pipe  in  the 
condenser  is  very  close  to  the  goose  neck  of  the  pan,  as  is  the  case 
with  most  of  the  vacuum  pans  in  use,  the  chilling  of  the  vapors  and 
of  the  spray  of  milk  rising  from  the  pan  is  so  sudden,  that  sugar 
crystals  are  prone  to  form  in  the  spray  and  along  the  walls  of  the 
pan.  These  crystals  either  stick  to  the  side  of  the  pan,  or  fall  back 
into  the  milk  where  they  later  multiply  and  cause  the  milk  to  become 
sugary.  Trouble  from  this  source  can  be  avoided  by  either  raising 
the  temperature  of  the  water  that  goes  to  the  condenser  which  is, 
however,  not  practical  under  most  conditions,  or  by  closing  the  holes 
in  that  portion  of  the  spray  pipe  which  is  nearest  the  pan.  This  can 
easily  be  done  by  wrapping  a  piece  of  galvanized  iron  or  tinplate 
around  the  portion  of  the  spray  pipe  to  be  closed,  or  by  filling  the 
holes  with  solder,  or  by  replacing  the  old  spray  pipe  by  a  new  and 
shorter  one,  properly  constructed. 

Superheating  at  End  of  Batch. — Sometimes  the  manufacturer 
is  persistently  troubled  with  the  appearance  of  crystals  in  the  con- 
densed milk  of  monstrous  size,  as  'large  as  rice  kernels;  this  con- 
dition arrives  usually  very  gradually.  During  the  first  few  days 
after  manufacture,  only  a  few  of  these  large  crystals  may  appear 
in  some  of  the  cans.  In  the  course  of  a  few  weeks,  all  of  the  cans 
may  contain  specimen  of  these  "rice  crystals"  which  increase  in 
number  until  the  entire  contents  of  the  cans  are  one  mass  of  "rice 
crystals,"  rendering  the  milk  unsalable.  The  direct  causes  of  this 
particular  kind  of  sugar  crystallization  are  excessive  concentration 
of  the  condensed  milk,  the  use  of  too  much  steam  pressure  in  the 
coi'ls  and  jacket  when  condensation  is  near  completion,  delay  in  the 
drawing  ofif  of  the  condensed  milk  from  the  pan,  and  leaky  steam 
valves  in  the  pipes  leading  to  jacket  and  coils. 

Toward  the  end  of  the  condensing  process  the  milk  becomes 


Condensed  Milk  and  Milk  Powder  i45 

heavy,  thick  and  syrupy,  and  boils  with  much  less  violence.  If,  at 
this  stage  of  the  process,  excessive  steam  pressure  is  used  in  the 
jacket  and  coils,  the  milk  is  superheated,  often  causing  the  precipi- 
tation of  "rice  crystals."  Again,  where  the  finished  condensed  milk 
is  drawn  from  the  pan  very  slowly,  either  owing  to  too  small  an 
outlet  in  the  bottom  of  the  pan,  or  because  the  milk  is  forced  to  run 
through  a  strainer  attached  to  the  outlet,  or  because  the  finished 
condensed  milk  is  retained  in  the  pan  as  the  result  of  an  accident, 
in  all  of  these  cases  there  is  danger  of  superheating,  and  therefore, 
of  the  production  of  these  large  crystals.  This  danger  is  especially 
great,  where  the  valves  of  the  steam  pipes  leading  to  the  jacket  and 
coils  are  leaking,  as  is  often  the  case.  The  avoidance  of  excessive 
concentration  and  the  removal  of  any  conditions  that  tend  to  expose 
the  finished  condensed  milk  to  excessive  heat  will  usually  prevent 
further  trouble  of  this  sort. 

Improper  Cooling.— The  method  used  for  cooling  the  sweet- 
ened condensed  milk  after  it  leaves  the  vacuum  pan  is  another 
important  factor  determining  the  smoothness  or  grittiness  of  the 
finished  product.  The  chief  principles  involved  here  are  the  rapidity 
and  extent  of  cooling  and  the  amount  of  agitation  to  which  the 
condensed  milk  is  subjected. 

In  order  to  fully  appreciate  the  importance  of  strict  attention 
to  details  in  the  cooling  process  of  sweetened  condensed  milk,  it 
should  be  understood,  that  the  formation  of  sugar  crystals  in  con- 
centrated solutions  is  enhanced  by  sudden  chilling  and  by  excessive 
agitation  of  these  solutions.  The  sudden  and  irregular  chilling  of 
a  part  or  all  of  the  sweetened  condensed  milk  in  the  cooling  cans  is 
the  result  of  the  use  of  badly  dented  cans,  poorly  fitting  paddles,  a 
warped  condition  of  the  pivots  on  which  the  cog  wheels  in  the 
bottom  of  the  cooling  vat  revolve,  too  cold  water,  and  the  application 
of  too  much  cold  water. 

The  paddles  must  scrape  all  parts  of  the  sides  of  the  cans,  from 
top  to  bottom.  This  is  possible  only  when  the  cans  are  intact  and 
their  sides  are  smooth  and  free  from  indentations.  The  paddles 
must  be  adjusted  properly  so  that  their  edges  fit  snugly  against  the 
sides  of  the  cans,  they  must  be  firmly  fastened  to  the  cross  bars  and 
forced  against  the  sides  of  the  cans  by  springs.  In  order  that  the 
cans  may  run  true  they  must  properly  fit  into  the  rim  of  the  cog 
wheels  in  the  bottom  of  the  cooling  vat  and  the  pivots  on  which  the 


146  Condensed  Milk  and  Milk  Powder 

cog  wheels  revolve  must  be  perpendicular.  If  the  pivots  are  warped, 
the  cog  wheels  cannot  run  true  and  the  cans  wobble;  this  causes 
uneven  and  incomplete  scraping  of  the  sides  of  the  cans  by  the 
paddles. 

The  water  in  the  cooling  vat  should  not  be  cold,  but  have  a 
temperature  of  about  90  degrees  F.  when  the  cans,  filled  with  the 
hot  condensed  milk,  are  set  into  the  vat.  The  cold  water  should 
flow  into  the  vat. slowly  and  be  evenly  distributed  throughout  the 
vat.  This  is  best  accomplished  by  the  installation  of  a  perforated 
pipe  running  the  entire  length  of  the  vat.  The  cooling  must  be 
gradual.     It  should  occupy  about  two  hours. 

Excessive  Stirring. — The  cans  should  revolve  slowly.  Rapid 
revolution  causes  excessive  agitation  of  the  condensed  milk,  which 
stimulates  the  formation  of  crystals.  About  five  revolutions  per 
minute  is  satisfactory.  In  order  to  make  more  effective  the  proper 
scraping  of  the  cans  by  the  paddles  when  the  cans  revolve  slowly, 
it  is  advisable  to  install  two  paddles  in  each  can,  touching  the 
periphery  of  the  can  on  opposite  sides. 

When  the  milk  has  been  cooled  to  between  60  and  70  degrees 
F.,  the  water  should  be  drawn  from  the  cooling  vat,  or  the  cans 
should  be  removed  at  once. 

Warming  Up  of  Too  Cold  Condensed  Milk. — Final'Iy,  if  the 
condensed  milk  is  cooled  to  too  low  a  temperature,  either  by  mis- 
take, or  as  the  result  of  the  cans  of  cooled  milk  standing  in  a  very 
cold  room  over  night,  so  that  the  condensed  milk  is  too  thick  to  run 
through  the  filling  machine,  it  is  best  to  warm  it  up  by  simply 
allowing  it  to  stand  in  a  warm  room.  The  practice  of  setting  the 
cans  back  into  the  cooling  tank  and  revolving  them  in  warm  water 
is  objectionable,  since  this  stirring  of  the  milk,  while  it  is  warming, 
seems  invariably  to  produce  wholesale  sugar  crystallization,  and 
therefore,  causes  the  condensed  milk  to  become  very  gritty. 

Settled  Sweetened  Condensed  Milk 

General  Description. — By  the  term  "settled  milk"  the  con- 
densed milk  man  refers  to  condensed  milk  which  has  precipitated 
and  thrown  down  a  portion  of  its  sugar,  forming  a  deposit  of  sugar 
crystals  in  the  bottom  of  the  can  or  barrel.  This  deposit  may  vary 
in  amount  from  a  very  thin  layer  to  a  layer  an  inch  deep  or  more, 
according    to    the    character    and    age    of    the    milk.    The    na- 


Condensed  Milk  and  Milk  Powder  i47 

ture  of  this  sediment  also  differs  in  different  cases  of 
settled  milk.  It  may  be  soft,  and  upon  stirring  may  mix  in  and 
dissolve  readily,  or  it  may  be  very  dry  and  hard,  in  which  case  it 
sticks  to  the  bottom  of  the  can  with  great  tenacity,  and  can  be 
removed  and  mixed  into  the  milk  with  difificulty  only.  Like  gritty 
milk,  settled  milk  is  a  very  common  condensed  milk  defect.  Though 
it  does  not  render  the  product  less  wholesome,  it  is  an  undesirable 
characteristic.  Such  milk  is  usually  rejected  on  the  market  and 
results  in  a  partial  loss  to  the  manufacturer. 

Causes  and  Prevention. — It  is  obvious,  for  reasons '  above 
referred  to,  that  the  conditions  leading  up  to  the  production  of  set- 
tled milk,  are  closely  related  to  those  that  cause  milk  to  become 
gritty.  Condensed  milk  cannot  drop  its  milk  sugar,  unless  the  latter 
is  present  in  the  form  of  crystals.  The  absence  of  crystals  then, 
means  that  condensed  milk  will  not  settle ;  but  experience  has  shown 
that  it  is  a  practical  impossibility  to  manufacture  sweetened  con- 
densed milk  which  contains  no  sugar  crystals.  Sugar  crystals  are 
always  present  in  it,  and  the  fact  that  the  milk  is  not  sandy  or  gritty, 
does  not  necessarily  mean  that  it  will  not  settle.  Nevertheless,  the 
removal  of  conditions  conducive  of  sandy  or  gritty  milk,  diminishes 
the  tendency  of  the  formation  of  sugar  sediment.  The  successful 
and  uniform  production  of  condensed  milk  that  does  not  settle, 
however,  involves  additional  conditions  that  are  not  controlled  by 
the  factors  causing  gritty  milk. 

Effect  of  Density  on  Sugar  Sediment. — One  of  the  chief  of 
these  conditions  is  the  density  of  the  condensed  milk.  The  thinner 
the  condensed  milk,  the  greater  the  difference  between  the  specific 
gravity  of  the  liquid  portion  and  that  of  the  sugar  crystals ;  there- 
fore, the  more  readily  will  the  crystals  sink  to  the  bottom.  The 
viscosity  of  thin  condensed  milk,  also,  is  less  than  that  of  thick  milk, 
offering  less  resistance  to  the  force  of  gravity  of  the  crystals.  In 
the  manufacture  of  sweetened  condensed  milk  that  has  the  proper 
density,  about  2.5  to  2.8  parts  of  fresh  milk  are  condensed  into  one 
part  of  condensed  milk.  If  the  evaporation  is  stopped  sooner,  so 
that  the  ratio  is  much  less  than  2.5  to  i,  the  condensed  milk  is 
usually  too  thin  to  hold  its  sugar  crystals  in  suspension. 

Effect  of  Fat  Content  on  Sugar  Sediment. — The  per  cent,  of  fat 
in  milk,  also,  influences  the  specific  gravity  of  the  condensed  milk, 
and  therefore,  has  some  effect  on  the  settling  of  the  sugar  crystals. 


148  Condensed  Milk  and  Milk  Powder 

although  to  a  relatively  slight  degree.  Nevertheless,  sweetened  con- 
densed skimmed  milk  will  settle  less  readily  than  sweetened  con- 
densed whole  milk. 

Effect  of  Cane  Sugar  Content  on  Sugar  Sediment. — The  per 
cent,  of  cane  sugar  materially  influences  the  specific  gravity  and  vis- 
cosity of  the  condensed  milk.  Milk  with  a  high  per  cent,  of  sucrose 
is  heavier,  more  viscous  and  drops  its  sugar  crystals  less  rapidly 
than  milk  with  a  low  per  cent,  of  sucrose. 

Turning  the  Cans  to  Prevent  Sugar  Sediment. — Concerns  who 
have  been  continually  troubled  with  settled  milk  often  resort  to  the 
practice  of  turning  their  cases  daily,  or  at  other  regular  intervals. 
This  keeps  the  precipitated  crystals  in  motion,  but  it  does  not  pre- 
vent the  settling  entirely.  Moreover,  milk  destined  to  settle,  as  the 
result  of  defects  in  the  process,  cannot  be  prevented  from  dropping 
its  crystals  after  it  leaves  the  factory.  Some  concerns  have  stooped 
to  printing  on  their  labels  statements  similar  to  the  following:  "A 
sediment  in  the  bottom  of  this  can  indicates  that  this  condensed  milk 
is  absolutely  pure  and  free  from  harmful  ingredients."  Advice  of 
the  above  denomination  is  obviously  ridiculous  as  well  as  untrue. 

Thickened  and  Cheesy  Sweetened  Condensed  Milk 

General  Description. — The  term  "thickened  and  cheesy"  con- 
densed milk  applies  to  condensed  milk  that  has  become  thick  and  in 
some  cases  solid.  This  is  a  very  common  trouble  with  milk  manu- 
factured in  late  spring  and  early  summer.  The  milk  thickens  soon 
after  its  manufacture  and  continues  thickening  until  it  assumes  the 
consistency  of  soft  cheese,  without  the  development  of  acid.  In  this 
condition  it  usually  has  a  peculiar  stale  and  cheesy  flavor,  disagree- 
able to  the  palate  of  the  consumer.  Such  milk  is  invariably  rejected 
on  the  market. 

Causes  and  Prevention:  Effect  of  Colostrum  on  Thickening. 
— It  has  been  suggested  that  this  spontaneous  thickening  is  due  to 
the  presence  in  the  fresh  milk  of  colostrum  milk,  because  this  defect 
appears  at  a  time  when  the  majority  of  the  cows  supplying  the  con- 
densery  freshen.  This  explanation  can  hardly  be  considered  cor- 
rect and  there  is  no  experimental  evidence  available  substantiating  it. 
If  the  presence  of  colostrum  milk  were  the  cause  of  it,  the  thickening 
would  take  place  during  the  process,  as  the  result  of  the  action  of 
heat  on  the  albumenoids.    This  is  not  the  case.    This  thickening  be- 


Condensed  Milk  and  Milk  Powder  149 

gins  some  days  and  often  some  weeks  after  manufacture  and  in- 
creases as  the  milk  grows  older. 

Effect  of  Cozv's  Feed-  on  Thickening. — Again,  the  cause  of  this 
defect  has  been  attributed  to  the  change  in  feed,  the  cows  being 
turned  from  dry  to  succulent  feed  at  the  time  when  this  tendency 
of  the  condensed  milk  to  thicken  occurs.  There  is  no  reliable  evi- 
dence, however,  of  how  the  succulent  pasture  grasses  on  which  the 
cows  feed  can  bring  about  this  thickening  action  in  the  condensed 
milk. 

Effect  of  Bacteria  on  Thickening. — A  third  and  far  more  rea- 
sonable explanation  is  that  this  thickening  is  the  result  of  a  fermen- 
tation process.  It  is  quite  probable  that  the  thickening  of  sweetened 
condensed  milk  is  closely  related  to  the  sweet-curdling  fermentation 
in  fresh  milk.  The  sweet-curdling  of  fresh  milk  is  a  fermentation 
characteristic  of,  and  frequent  during  late  spring  and  summer.  It  is 
caused  by  certain  species  of  bacteria  which  are  capable  of  producing 
a  rennet-like  enzyme,  which  has  the  power  to  curdle  milk  in  the  sweet 
state.  These  bacteria  are  known  to  be  closely  associated  with  dirt 
and  filth,  especially  from  the  feces,  and  gain  access  to  the  milk  usu- 
ally on  the  farms  where  the  production  and  handling  of  milk  is  not 
accomplished  under  most  sanitary  conditions. 

It  is  further  known,  as  the  result  of  analyses  that,  in  spite  of  the 
large  per  cent,  of  cane  sugar  which  sweetened  condensed  milk  con- 
tains, the  bacteria  in  it  increase  with  the  age  of  the  milk.  The 
thickening  of  the  sweetened  condensed  milk  in  early  summer,  there- 
fore, very  probably  is  the  result  of  a  slow  curdling  of  its  casein, 
caused  by  enzymes  which  are  produced  by  bacteria.  It  has  further 
been  demonstrated  that  condensed  skim  milk  thickens  more  readily 
than  condensed  whole  milk,  which  may  be  explained  by  the  fact  that 
condensed  milk  without  butter  fat  represents  a  more  favorable  me- 
dium for  bacterial  growth.  Furthermore,  it  has  been  conclusively 
demonstrated  by  the  writer  and  others  that  the  addition  of  cane  su- 
gar to  condensed  milk,  in  excess  of  that  present  in  normal  condensed 
milk,  greatly  retards  thickening.  This  fact  suggests  that  the  higher 
per  cent,  of  sucrose  has  an  inhibiting  effect  on  the  enzyme-produc- 
ing bacteria,  and  perhaps,  on  the  action  of  the  enzyme  itself.  This 
condensed  milk  defect  can  be  prevented  entirely  by  using,  during 
the  summer  months,  eighteen  pounds  of  sucrose  per  one  hundred 


150  Condensed  jMilk  and  AIilk  Powder 

pounds  of  fresh  milk,  so  that  the  condensed  milk  contains  about  45 
per  cent,  sucrose. 

Owing  to  the  poor  keeping  quality  of  the  summer  condensed 
milk,  it  is  advisable  not  to  store  any  milk  made  during  these  months, 
but  to  sell  it,  even  at  a  small  margin,  as  fast  as  it  is  manufactured. 

Effect  of  Finishing  in  Pan  With  High  Steam  Pressure  on 
Thickening. — Abnormally  thick  condensed  milk  is  also  the  result 
of  overheating  the  condensed  milk  in  the  vacuum  pan  toward  the 
close  of  the  process.  The  batch  should  be  finished  with  low  steam 
pressure  in  the  jacket  and  coils,  not  to  exceed  five  pounds  of  pres- 
sure, and  the  milk  should  be  drawn  from  the  pan  at  once  after  con- 
densation is  completed. 

Effect  of  Age  on  Thickening. — Finally,  all  sweetened  condensed 
milk  has  a  tendency  to  thicken  with  age.  Exposure  to  high  storage 
temperature  (summer  heat)  hastens  this  action.  The  rapidity  of 
thickening  in  storage  increases  with  the  increase  in  temperature. 
This  tendency  is  very  much  reduced,  therefore,  by  protecting  the 
goods  from  high  temperatures  and  by  storing  them  below  60  degrees 
F.     (See  Chapter  on  "Storage,"  page  112). 

Lumpy  Sweetened  Condensed  Milk 

General  Description. — Lumps  of  varying  denominations  are 
not  infrequently  found  in  sweetened  condensed  milk.  They  may  be 
soft  and  permeate  the  contents  of  the  can  throughout,  or  may  appear 
especially  in  the  form  of  a  "smear"  along  the  seams  of  the  can ;  or 
again,  they  may  float  on  the  surface,  in  which  case  they  are  usually 
hard  and  cheesy,  and  either  white  or  yellow  in  color.  Their  pres- 
ence gives  the  contents  of  the  can  an  unsightly  appearance  at  best, 
and  in  many  cases,  they  spoil  its  flavor.  They  naturally  suggest  to 
the  consumer  that  something  is  wrong  with  the  condensed  milk,  and 
cause  him  to  reject  the  whole  package. 

Causes  and  Prevention. — The  chief  causes  of  lumpy  con- 
densed milk  are :  poor  quality  of  fresh  milk,  unclean  pipes  in  fac- 
tory, milk  from  fresh  cows,  acid  flux  in  tin  cans,  and  unclean  and 
contaminated  tin  cans. 

Poor  Quality  of  Fresh  Milk  and  Unclean  Factory  Conditions. — 
Upon  opening  the  can  of  condensed  milk,  even  shortly  after  it  is 
filled,  the  lid  is  covered  with  large  and  small  lumps  and  specks  stick- 


Condensed  Milk  and  Milk  Powder  151 

ing  to  the  tin,  presenting  a  very  uninviting  appearance.  This  condi- 
tion can  usually  be  traced  back  to  a  poor  quality  of  fresh  milk,  con- 
taining too  much  acid.  Very  often,  too,  the  cause  lies  in  the  factory 
itself,  where  it  is  due  to  lack  of  cleanliness.  A  thorough  inspection 
of  milk  tanks,  milk  pipes  and  pumps  generally  shows  accumula- 
tions of  remnants  of  milk  which  get  into  the  milk  of  the  succeeding 
batch.  Where  this  condition  exists,  it  is  noticeable  that  the  first 
batch  of  the  day  contains  more  specks  and  lumps  than  the  succeeding 
ones.  These  lumps  do  not,  as  a  rule,  grow  larger  in  size  nor  increase 
in  number  with  the  age  of  the  condensed  milk,  but  they  injure  its 
appearance  to  the  eye,  and  certainly  cannot  add  to  the  wholesome- 
ness  of  the  milk.  They  might  easily  become  the  cause  of  the  for- 
mation of  ptomains.  A  more  rigid  inspection  of  all  the  fresh  milk 
as  it  arrives  at  the  factory  and  a  thorough  scouring  of  all  milk  tanks 
and  milk  pumps,  pipes  and  conveyors  usually  prevents  the  recur- 
rence of  this  defect. 

Milk  From  Fresh  Cozvs. — During  early  spring  there  is  a  strong 
tendency  of  the  jacket  and  coils  in  the  vacuum  pan  to  become  coated 
with  a  thick  layer  of  gelatinous  and  lumpy  milk.  This  is  probably 
due  to  the  fact  that  milk  during  these  months  comes  largely  from 
freshened  cows  and  may  contain  some  colostrum  milk  which  coagu- 
lates when  subjected  to  heat,  or  that  the  proteids  of  milk  from  these 
fresh  cows  are  abnormally  sensitive  to  heat.  This  thickened  material 
usually  does  not  leave  the  pan  until  most  of  the  condensed  milk  has 
been  drawn  ofif.  It,  therefore,  appears  in  the  last  one  or  two  cool- 
ing cans.  If  the  mjlk  in  these  cans  is  mixed  with  the  rest  of  the 
condensed  milk,  the  lumps  will  appear  again  in  the  tin  cans. 
The  last  cans  drawn  from  the  pan  should,  therefore,  be  kept  sepa- 
rate. The  contents  of  these  remnant  cans  may  be  redissolved  in  hot 
water  and  should  be  recondensed  in  a  succeeding  batch.  In  this  way 
the  manufacturer  sustains  practically  no  loss.  In  order  to  prevent 
these  lumps  from  getting  into  the  cooling  cans,  some  factories  at- 
tach a  strainer  to  the  outlet  of  the  pan.  This  practice  is  as  unnec- 
essary, as  it  is  damaging  to  the  milk  in  the  pan.  The  straining  great- 
ly retards  the  removal  of  the  milk  from  the  pan,  and  the  milk  is 
held  in  the  hot  pan  so  long,  as  to  cause  partial  superheating  which  is 
otherwise  detrimental  to  its  quality. 


152 


Condensed  Milk  and  Milk  Powder 


COMPARATIVE  COMPOSITION    OF  GELATINOUS    COATING    OF    THE 

JACKET   AND   COILS   AND   OF   NORM  AL  CONDENSED  M  ILK  OF 

THE   SAME   BATCH,    MADE    APRIL    23,    1908 


Moisture 

Lactose 

Fat 

Curd 

Ash 

Acid 

Sucrose 


Coating  of  jacket 
and  coils 
24.76  per  cent. 
13.12 

Q-50 

8.14         " 
1.42 

•33 
41.36 

98.63  per  cent. 


Normal  condensed 
milk 
30.34  per  cent. 
13.16 
7-44 

7-30        " 
1.80 
.40 
40.02        " 


100.46  per  cent. 


The  above  analyses  were  made  in  order  to  determine  the  dif- 
ference in  chemical  composition  between  that  part  of  the  batch 
which,  in  the  spring  qf  the  year,  forms  a  gelatinous  coating  on  the 
jacket  and  coils  and  that  part  which  remains  normal.  The  figures 
do  not  show  as  great  a  difference,  as  the  physical  comparison  of  the 
two  products  would  suggest.  Possibly  the  most  significant  point 
these  analyses  show  is  that,  while  the  proteids  in  the  coating  are 
higher,  the  ash  is  lower  than  in  the  normal  condensed  milk. 

A  large  portion  of  the  ash  of  milk  is  present  in  chemical  com- 
bination with  the  casein,  which  does  not  curdle  by  heat,  while  the 
albumin,  which  is  coagulated  by  heat,  contains  only  a  very  small 
amount  of  ash.  Therefore,  the  fact  that  an  increase  in  the  proteids 
of  this  gelatinous  coating  is  accompanied  by  a  decrease  in  the  ash 
content,  would  suggest  that  the  proteids  of  the  coating  of  the  jacket 
and  coils  consist  of  more  albumin  and  less  casein  than  the  proteids 
of  the  normal  condensed  milk  of  the  same  batch.  Since  this  coating 
of  the  jacket  and  coils  occurs  only  in  the  spring  of  the  year,  when 
most  of  the  cows  freshen,  it  is  reasonable  to  assume  that  this  coat- 
ing is  the  result  of  the  acceptance  at  the  factory  of  milk  too  soon 
after  calving  and  which  contains  excessive  quantities  of  proteids 
and  other  substances  which  arc  highly  sensitive  to  heat,  such  as 
albumin,  colostrum,  etc. 

Excess  of  Acid  in  Condensed  Milk  and  Acid  Flux  in  Tin  Cans. 
— The  presence  in  the  condensed  milk  of  organic  and  mineral  acids, 


Condensed  Milk  and  Milk  Powder  153 

in  excess  of  the  amount  which  normal  fresh  milk  contains,  is  con- 
ducive of  the  formation  of  lumps. 

Excessive  amounts  of  acid  in  condensed  milk  may  be  the  result 
of  fermentations,  usually  due  to  a  poor  quality  of  sugar,  or  of  the 
use  of  acid  flux  in  the  making  and  sealing  of  the  tin  cans.  Con- 
densed milk  that  shows  acid  or  gaseous  fermentation  usually 
contains  lumps.  The  acid  which  it  develops  as  the  result  of  the 
fermentation,  curdles  the  casein  with  which  it  comes  in  contact. 

One  of  the  most  common  channels  through  which  condensed 
milk  may  become  contaminated  with  acid  mechanically,  is  the  use 


Figr.  49.     Machine  for  rinsing:  and  sterilizing:  tlie  tin  oans 

Courtesy  of  The  Sprague  Canning  Machinery  Co. 

of  cans,  in  the  manufacture  of  which  acid  ilux  was  used.  The  acid 
flux  generally  used  contains  zinc  chloride.  The  flux  precedes  the 
solder  and  some  of  it  is  bound  to  sweat  through  the  seams  into  the 
interior  of  the  cans.  Zinc  chloride  is  a  highly  poisonous  product 
and  its  use  in  the  manufacture  of  tin  cans,  which  are  intended  for 
receptacles  of  human  food,  should  be  prohibited  by  law.  Aside  from 
its  injurious  effect  on  the  health  and  life  of  the  consumer,  its  pres- 
ence, even  in  small  quantities  in  condensed  milk,  is  a  detriment  to 
its  market  value.  In  such  cans  there  accumulate,  usually  along  the 
seams,  lumps  and  smeary  substances  which  have  been  found  to 
consist  of  casinate  of  zinc. 

Most  commercial  soldering  fluxes  consist  largely  of  zinc 
chloride  and  are  highly  acid,  although  many  of  these  are  advertised 
as  acid-free  fluxes.     In  order  to  avoid  condensed  milk  containing 


154  CoNDKNSED  Milk  and  Milk  Powder 

lumps  from  this  source,  cans  should  be  used,  in  the  manufacture  of 
which  a  strictly  acid-free  flux  is  used  and  which  are  sealed  with 
acid-free  flux.  Dry,  powdered  resin  or  resin  dissolved  in  alcohol  or 
gasoline  are  harmless  in  this  respect  and  are  just  as  effective  fluxes, 
as  acid  flux. 

Unclean  and  Contaminated  Tin  Cans. — Finally.  thcM-e  frequently 
appear  in  sweetened  condensed  milk,  species  of  lumps  which  are 
firm  and  cheesy  and  which  usually  float  on  top  of  the  milk  in  the 
can.  These  are  called  buttons.  Some  are  white,  others  are  yellow. 
These  buttons  appear  in  old  milk  more  frequently  than  in  milk  that 
has  been  in  storage  for  a  short  time  only.  They  grow  in  size  and 
sometimes  one  "button"  covers  the  entire  surface  of  the  condensed 
milk  in  the  can.  Their  origin  is  not  well  understood,  but  they  are 
supposed  to  be  the  result  of  fungus  growth.  It  is  not  improbable 
that  they  are  produced  by  molds,  the  spores  of  which  gain  access  to 
the  condensed  milk  in  the  factory,  or  to  the  cans  before  they  are 
filled.  These  "buttons"  appear  in  the  canned  goods  and  in  the 
barrel  goods.  Their  occurrence  can  be  minimized  by  protecting 
the  condensed  milk  and  the  empty  cans  from  dust  and  other  im- 
purities or  by  sterilizing  the  cans  immediately  before  use,  and  by 
parafifining  and  thoroughly  steaming  the  barrels  before  filling. 

Blown,  or  Fermented  Sweetened  Condensed  Milk 

General  Description. — One  of  the  most  disastrous  troubles 
in  the  manufacture  of  sweetened  condensed  milk  is  the  appearance 
of  "swell  heads."  This  term  is  applied  to  cans  of  condensed  milk, 
the  contents  of  which  have  undergone  gaseous  fermentation,  the 
resulting  pressure  causing  the  ends  of  the  cans  to  bulge  or  swell, 
and  frequently  to  burst  open  the  seams.  In  the  case  of  barrel  goods, 
the  pressure  may  cause  the  barrel  head  to  blow  out.  This  gaseous 
fermentation  is  usually,  though  not  always,  accompanied  by  the 
development  of  acid  and  the  formation  of  lumps. 

This  fermented  milk  is  worthless  for  any  purpose  and  means 
a  total  loss  to  the  manufacturer.  The  loss  is  generally  augmented 
by  the  fact  that  this  trouble  does  not  become  noticeable  at  once; 
its  development  requires  several  weeks,  so  that  large  quantities  of 
condensed  milk  may  have  been  manufactured  before  it  is  apparent 
that  the  milk  is  defective.  Some  of  the  goods  may  have  reached 
the  market  before  the  cans  begin  to  swell,  in  Which  case  the  repu- 


CoNDKNSED  Milk  and  Milk  Powder  155 

tation  of  the  respective  brand  is  jeopardized.  In  some  instances 
entire  batches  show  this  defect,  while  in  others  only  a  few  cans  or 
cases  of  each  batch  are  blown. 

Causes  and  Prevention. — This  defect  may  be  brought  about 
through  various  channels.  In  most  cases  it  is  due  to  contamination 
of  the  milk,  on  the  farm  or  in  the  factory,  with  specific  micro- 
organisms which  are  capable  of  fermenting  one  or  more  of  its 
ingredients,  in  spite  of  the  preservative  action  of  the  sucrose;  or 
the  condensed  milk  may  contain  highly  fermentable  substances  such 
as  glucose  or  invert  sugar,  so  that  the  germs  normally  present  in 
the  condensed  milk  become  active  and  produce  gas ;  or  the  milk 
may  not  be  condensed  to  a  sufficient  degree  of  concentration,  or  may 
not  contain  adequate  quantities  of  sucrose,  to  render  it  immune  to 
the  bacteria  normally  present.  The  cans  may  also  bulge  without 
bacterial  action,  as  the  result  of  exposure  to  a  wide  range  of  tem- 
peratures, causing  mechanical  contraction  and  expansion  of  the 
contents. 

Contamination  With  Specific,  Gas-Producing  Bacteria  and 
Yeast. — This  is  by  far  the  most  common  cause  of  blown  milk.  While 
the  micro-organisms  which,  under  normally  sanitary  production  of 
milk  and  factory  conditions,  gain  access  to  the  condensed  milk,  are 
largely  inhibited  and  do  not  ferment  the  sweetened  condensed  milk, 
there  are  certain  specific  forms  of  bacteria  and  yeast  whose  growth 
is  not  retarded  by  the  concentrated  sugar  solution  of  this  product. 
Contamination  of  the  condensed  milk  with  these  specific  organisms  is 
usually  the  result  of  highly  unsanitary  conditions  in  the  handling  of 
the  condensed  milk. 

The  products  of  fermentation  depend  on  the  particular  type 
and  species  of  micro-organisms  involved.  In  most  cases  the  sucrose 
is  the  chief  constituent  attacked,  but  the  lactose,  also,  is  capable  of 
gaseous  fermentation,  though  instances  of  lactose  fermentation  in 
sweetened  condensed  milk  are  not  common. 

The  gaseous  fermentation  of  lactose  is  largely  caused  by  bac- 
teria, yeast  and  molds  which  contain  the  lactose-splitting  enzyme 
"lactase,"  which  has  the  power  of  hydrolyzing  the  lactose.  While 
the  species  of  organisms  which  cause  lactic  acid  fermentation  from 
lactose  are  very  numerous,  those  containing  the  enzyme  lactase  and 
thereby  causing  gaseous  fermentation  from  lactose,  are  less  fre- 
quent, at  least,  as  far  as  their  access  to  milk  and  condensed  milk  is 


156  Condensed  Milk  and  Milk  Powder 

concerned.  It  is  generally  understood,  though  not  experimentally 
proven,  that  species  of  micro-organisms  which  do  not  contain  the 
enzyme  lactase  have  no  gas-producing  action  on  lactose. 

The  great  majority  of  cases  of  gaseous  fermentation  of  sweet- 
ened condensed  milk  are  the  result  of  the  action  of  micro-organisms 
on  the  sucrose,  especially  those  which  contain  the  enzyme  *'inver- 
tase."  The  majority  of  yeasts  secrete  invertase  and  ferment  sucrose, 
producing  alcohol  and  carbon  dioxide  to  the  same  extent  as  in  the 
case  of  glucose  fermentations.  The  process  is  considerably  slower, 
however,  especially  at  the  start,  owing  to  the  fact  that  inversion  of 
the  sucrose  must  precede  fermentation.  For  this  reason  gaseous 
fermentations  of  sweetened  condensed  milk  do  not  become  notice- 
able until  the  product  is  one  or  several  weeks  old. 

Contamination  With  Yeast  on  the  Farm. — In  most  cases  of 
yeast  fermentations  of  sweetened  condensed  milk,  the  source  of 
contamination  lies  in  the  factory.  While  such  contamination  may 
and  often  does  occur  on  the  farm,  the  yeast  .cells,  though  they  may 
be  spore-bearing,  are  destroyed  by  the  heat  to  which  the  fresh  milk 
is  subjected  in  the  forewarmers  and  before  it  reaches  the  vacuum 
pan.  The  thermal  death  point  of  all  forms  of  yeast  which  have 
come  to  the  attention  of  the  writer  in  connection  with  a  vast  num- 
ber of  investigations  of  fermented  condensed  milk  was  below  180 
degrees  F.  If  all  the  milk  is  properly  heated  in  the  forewarmers  to 
190  degrees  F.  or  over,  there  is.  therefore,  little  danger  of  fermented 
milk,  caused  by  contamination  of  the  fresh  milk  on  the  farm  with 
yeast.  If,  however,  the  heating  is  incomplete,  or  if  some  of  the  milk 
passes  into  the  vacuum  pan  without  having  been  properly  heated, 
there  is  danger  of  milk,  contaminated  with  these  yeasts,  to  result  in 
fermented  condensed  milk. 

Contamination  witli  Yeast  in  the  Factory.— As  previously' 
stated,  yeast  fermentation  of  condensed  milk  can  almost  invariably 
be  traced  back  to  contamination  in  the  factory.  After  the  milk 
leaves  the  forewarmers,  or  hot  wells,  it  is  never  again  heated  to 
temperatures  high  enough  to  destroy  these  destructive  yeast  cells. 
The  channels  through  which  yeast  contamination  may  occur  in  the 
factory  are  many. 

Contaminated  Sugar. — The  sucrose  itself  may  be  contaminated 
with  yeast.    This  is  frequently  the  case  and  especially  so  if  the  sugar 


Condensed  Milk  and  Milk  Powder 


157 


is  exposed  to  dampness,  and  if  flies,  bees,  ants  or  cockroaches  have 
access  to  it. 

Again,  the  sugar  may  reach  the  milk  through  a  sugar  chute. 
The  lower  end  of  the  chute  is  usually  located  directly  over  the 
steaming  milk  in  the  hot  well.  The  vapors  arising  from  below  may 
be  condensed  in  the  chute,  causing  its  inside  walls  to  become  damp, 
and  sugar  will  adhere  to  the  damp  surface,  forming  a  crust.  If  the 
crust  is  not  removed  daily,  its  contamination  with  yeast  and  other 
dangerous  micro-organisms  is  almost  inevitable  and  whenever  this 
crust  peels  oflf  and  drops  into  the  milk,  the  contamination  may  be 
carried  into  the  finished  product,  giving  rise  to  gaseous  fermentation. 


Fig.  51.     Yeast  cells  causing 
gaseous  fermentation 

This  species  is  capable  of  fer- 
menting sugar  solutions  contain- 
ing   S5%   sucrose 

Fig.  50.     Gaseous  fermentation  in  sweetened 
condensed  milk 

Contaminated  Machinery  and  Milk  Conveyors. — Remnants  of 
milk  may  lodge  in  the  condenser,  in  the  vacuum  pan,  in  the  pipes 
conveying  the  milk  and  condensed  milk,  in  the  cooling  cans  or  coils, 
in  the  supply  tank  of  the  filling  machine,  or  the  filling  machine  itself. 
These  remnants  are  all  subject  to  contamination  and  may  become 
the  source  of  fermented  condensed  milk.  The  strictest  attention  to 
scrupulous  cleanliness  and  continuous  inspection  of  all  parts  of  con- 
veyors and  apparatus  which  come  in  contact  with  the  milk  are  the 
only  consistent  safeguards  against  trouble  from  this  source. 

Contamination  Through  "Cut-opens". — It  is  customary  to  empty 
the  contents  of  sample  cans  which  are  cut  open  for  any  purpose, 


158  Condensed  Milk  and  Milk  Powder 

back  into  the  condensed  milk  of  succeeding  batches.  If  these  sam- 
ples happen  to  be  contaminated  with  the  fermenting  germs,  the 
defect  is  naturally  propagated  from  batch  to  batch  and  it  is  exceed- 
ingly difficult  to  locate  the  source  of  the  trouble.  It  is  obvious  that 
all  suspicious  "cut-opens"  should  be  rejected  and  that  all  "cut-opens" 
that  are  utilized  should  be  emptied  into  the  hot  well  where  their 
contents  are  boiled  up  again. 

Dangerous  Effect  of  Poor  Quality  of  Sugar. — Sweetened  con- 
densed milk  is  not  sterile.  There  is  no  part  of  the  process  that 
would  render  it  sterile  and,  from  the  time  it  leaves  the  vacuum  pan 
to  the  time  when  the  tin  cans  are  hermetically  sealed,  it  is  exposed 
to  .contamination  with  microbes,  even  though  the  factory  observes 
the  most  rigid  attention  to  scrupulous  sanitation  and  cleanliness. 
Most  of  these  microbes  are  harmless  and  their  growth  is  inhibited 
by  the  preservative  action  of  the  cane  sugar.  If,  however,  a  poor 
quality  of  sucrose  is  used,  which  may  contain  traces  of  invert  sugar, 
or  acid,  etc.,  many  of  these  common  species  of  micro-organisms, 
harmless  in  normal  condensed  milk,  find  an  opportunity  to  develop 
and  cause  gaseous  fermentation.  The  presence  of  invert  sugar 
makes  unnecessary  the  action  of  invertase  in  order  to  start  fer- 
mentation ;  thus,  microbes  which  do  not  secrete  invertase  and  are 
otherwise  harmless,  may  become  detrimental  in  the  presence  of  in- 
vert sugar,  added  to  the  milk  in  the  form  of  a  poor  quality  of  cane 
sugar.  In  a  similar  way  the  use  in  condensed  milk  of  commercial 
glucose,  as  a  substitute  of  a  part  of  the  cane  sugar,  and  in  order  to 
reduce  the  cost  of  manufacture,  is  bound  to  cause  disastrous  re- 
sults. Nothing  but  the  best  refined,  granulated  sucrose  should  be 
used,  the  best  is  the  cheapest. 

Dangerous  Effect  of  High  Acid  in  Milk. — Acids  have  the  power 
of  inverting  sucrose.  The  inversion  by  acid  is  especially  active  in 
the  presence  of  heat.  The  milk  in  the  vacuum  pan  is  condensing  at 
130  to  150  degrees  F.  These  temperatures  are  most  favorable  to 
inversion  of  a  portion  of  the  sucrose  in  the  presence  of  acid.  The 
higher  the  acid  content  of  the  milk,  the  more  active  is  the  inversion. 
Since  invert  sugar  is  the  very  ingredient  necessary  to  cause  bacterial 
action  in  the  finished  product,  it  is  essential  that  the  acidity  of  the 
milk  to  be  condensed,  should  be  held  down  to  the  minimum  in  order 
to  avoid  trouble  from  this  source. 


Condensed  MiIvK  and  Milk  Powder  159 

Contamination  with  Butyric  Acid  Bacteria. — Frequently  the 
troublesome  microbe  is  not  a  yeast,  but  belongs  to  a  species  of  bac- 
teria highly  resistent  to  heat,  and  which  fail  to  be  destroyed  by 
heating  the  milk  to  the  boiling  point.  In  this  case,  the  contamination 
usually  originates  on  the  farm.  Organisms  of  this  kind,  which  infest 
the  milk  on  the  farm  in  this  connection,  largely  belong  to  the  butyric 
acid  group.  The  most  prominent  among  them  are  Granulobacillus 
saccharo-butyricus  mobilis  or  Bacillus  saccharobutyricus,  Bacillus 
esterificans.  Bacillus  dimorphobutyricus.  The  putrefactive  forms 
of  butyric  acid  organisms,  such  as  Bacillus  putrificus,  Plectridium 
foetidum,  Plectridium  novum,  etc.,  do  not  seem  to  thrive  in  sweet- 
ened condensed  milk. 

The  contamination  may  occur  from  dust  of  hay  and  other 
fodder,  grain,  bedding,  or  the  unclean  coat  of  the  udder  and  sur- 
rounding portions  of  the  animal,  or  from  milking  with  wet  and 
unclean  hands,  or  from  remnants  of  milk  in  unclean  utensils. 

It  is  noticeable  that  the  great  majority  of  cases  of  blown  milk 
appear  during  late  summer  and  early  fall,  when  the  crops  are  har- 
vested and  the  air  in  the  barn  is  frequently  loaded  with  dust  from 
the  incoming  crops.  Gelatin  plates  exposed  in  the  stable  before  and 
during  the  filling  of  silos  showed  an  enormous  increase  of  colonies 
on  the  plates  exposed  during  the  filling  of  the  silos.  Milk  drawn 
under  such  conditions  is  naturally  subjected  to  excessive  contam- 
ination, unless  special  precautions  are  observed. 

A  very  common  source  of  these  butyric  acid  organisms  also  is 
remnants  of  milk  in  pails,  strainers,  coolers,  cans  and  any  other 
utensils  with  which  the  milk  may  come  in  contact,  also  polluted 
water  used  for  rinsing  the  utensils.  The  cheese-cloth  strainer, 
owing  to  the  fact  that  it  is  difficult  to  thoroughly  clean  and  that  it  is 
very  seldom  really  clean,  is  a  very  serious  menace  in  this  respect. 
Under  average  farm  conditions,  unless  a  new  cloth  strainer  is  used 
at  each  milking,  it  is  safe  to  condemn  it  entirely  and  to  recommend 
the  use  of  a  fine  wire  mesh  strainer  containing  about  eighty  meshes 
to  the  inch.  On  some  farms  the  milk  is  held  in  a  set  of  old  cans 
which  are  kept  on  the  farm  and  which  never  reach  the  can  washer 
at  the  factory.  Just  before  hauling  time  these  cans  are  emptied  into 
the  clean  cans  from  the  factory.  These  old  cans  are  often  not 
washed  properly  and  sometimes  not  at  all.  The  remnants  of  milk 
in  these  cans  breed  these  undesirable  germs  and  contaminate  the 


i6o  Condensed  Milk  and  Milk  Powder 

fresh  milk.  It  is  obvious  that  such  a  practice  is  bound  to  jeopardize 
the  quahty  and  Hfe  of  the  finished  product  and  may  constitute  a 
continuous  cause  of  blown  milk. 

Effect  of  Amount  of  Sucrose. — Since  the  sucrose  contained  in 
sweetened  condensed  milk  is  the  chief  agent  preserving  it.  it  is  ob- 
vious that  enough  of  it  must  be  added  to  insure  adequate  preserva- 
tive action.  Experience  has  shown  that  about  39  to  40  per  cent,  of 
sucrose  is  required  to  preserve  the  condensed  milk  under  average 
conditions.  A  higher  per  cent,  of  sucrose  would  naturally  intensify 
the  preservative  action  and  inhibit  the  growth  of  the  bacteria 
normally  present  more  completely;  but  if  enough  sugar  were  added 
to  also  inhibit  the  growth  of  and  make  harmless  those  violent  gas 
producing  butyric  acid  bacteria  and  yeast  cells,  which  thrive  in 
sweetened  condensed  milk  containing  40  per  cent,  sucrose,  the 
product  would  be  objectionable  from  the  consumer's  point  of  view. 
The  logical  avoidance  of  "swell  heads"  as  the  result  of  these  un- 
desirable germs,  therefore,  must  ever  lie  in  prevention,  rather  than 
cure.  The  sanitary  standard  of  production  on  the  farm  and  of  the 
process  in  the  factory  must  be  raised  to  and  maintained  on  a  level 
where  the  milk  is  protected  from  contamination  with  these  micro- 
organisms. 

The  writer^  has  isolated  yeast  from  fermented  sweetened  con- 
densed milk  that  produced  vigorous  gas  formation  in  media  contain- 
ing as  high  as  85  per  cent,  sucrose  (600  grams  sucrose  in  100  c.c. 
whey  bouillon). 

Effect  of  Too  Thin  Condensed  Milk. — Condensed  milk  that  is 
too  thin  is,  also,  prone  to  start  fermenting,  since  it  is  deficient  in 
the  chief  preserving  agents,  i.  e.,  density  and  per  cent,  of  sucrose. 
It  is  not  safe  to  put  goods  on  the  market,  with  a  ratio  of  concen- 
tration much  less  than  2.5:1. 

Effect  of  Excessively  Loiv  Temperatures. — The  cans  of  sweet- 
ened condensed  milk  may  also  bulge  in  the  case  of  cans  with  non- 
hermetical  seals,  exposed  successively  to  excessive  cold  and  to  room 
temperature.  In  this  case,  the  condensed  milk  is  entirely  normal 
and  unaffected,  and  the  bulging  is  the  result  of  mechanical  con- 
traction and  expansion  by  cold  and  heat.  This  is  possible  only 
where  the  seal  of  the  cans  is  not  entirely  hermetical.     In  the  case  of 


Hunziker,  Results  not  published 


Condensed  Milk  and  Milk  Powder  i6i 

the  Gebee  seal  with  the  burr  cap,  and  the  McDonald  seal  with  the 
friction  cap,  the  seal  is  not  absolutely  air-tight.  While  the  pores 
between  cap  and  can  are  microscopic  in  size,  and  not  large  enough 
to  permit  the  contents  from  leaking  out,  they  are  sufficient  to  admit 
air.  The  cans  are  usually  filled  with  the  condensed  milk  at  a  tem- 
perature of  about  70  degrees  F.  If  the  filled  and  sealed  cans  are 
exposed  to  a  very  low  temperature,  as  may  be  the  case  in  winter,  in 
store  houses  or  in  transit,  the  milk  and  the  air  in  the  cans  contract. 
This  contraction  is  intensified  by  the  fact  that  the  sweetened  con- 
densed milk  does  not  freeze.  Its  concentration  is  so  great  that  its 
freezing  point  is  usually  below  the  most  extreme  cold  storage  tem- 
perature. This  contraction  of  milk  and  air  in  the  cans  produces  a 
partial  vacuum,  causing  air  to  be  drawn  into  the  cans  through  the 
microscopic  openings  of  the  seal.  When  the  cans  are  subsequently 
moved  into  places  with  a  more  moderate  temperature,  the  milk  and 
the  air  in  the  cans  expand,  but  the  milk  on  the  inside  of  the  cans 
forms  a  seal  preventing  the  escape  of  the  surplus  air.  The  result 
is  that  the  ends  of  the  cans  bulge.  This  phenomenon  has  been  ex- 
perimentally determined  by  the  author.^  While  the  contents  of  such 
cans  are  perfectly  normal,  the  package  suggests  fermented  milk  and 
may  be  rejected  on  the  market. 

It  is  evident,  from  the  above  data,  that  the  swelling  of  the  cans, 
as  the  result  of  exposure  to  excessively  low  temperatures,  can 
readily  be  avoided,  either  by  protecting  the  cans  against  excessive 
cold,  or  by  using  cans  that  are  sealed  with  solder.  The  solder- 
seals  are  hermetical  so  that  no  air  can  be  drawn  into  the  cans  when 
a  partial  vacuum  is  formed  in  their  interior  as  the  result  of  the 
contraction  of  air  and  milk. 

Rancid  Sweetened  Condensed  Milk 

General  Description. — ^Sweetened  condensed  milk  may  de- 
velop a  distinctly  rancid  flavor  and  odor,  a  defect  which  renders 
it  unmarketable. 

Causes  and  Prevention. — While  the  exact  causes  of  the  de- 
velopment of  rancidity  in  dairy  products  are  as  yet  not  well 
understood,  it  has  been  demonstrated  experimentally  that  rancidity 
as  well  as  other  allied  off-flavors,  such  as  oiliness,  tallowiness,  fish- 
iness,  etc.,  are  closely  associated  with  the  decomposition  of  some  of 


"  Hunziker,  Results  not  published 


1 62  Condensed  Milk  and  Milk  Powder 

the  milk  fats.  Formerly  these  defects  were  attributed  to  the  break- 
ing down  of  the  glycerides  of  the  volatile  fatty  acids,  but  more  recent 
experimental  data  indicate  that  the  olein  is  the  most  unstable  fat, 
owing  to  the  ease  with  which  it  yields  to  oxidation,  and  that  the 
splitting  up  of  the  glycerides  of  oleic  acid  in  all  probability  is  largely 
responsible  for  the  different  shades  of  rancidity  which  develop  in 
dairy  products  under  certain  combinations  of  conditions. 

According  to  the  best  authorities,  there  are  many  agents  which 
may  be  active  in  the  production  of  rancidity.  The  fact  that  in  ran- 
cid butter  are  usually  found  to  predominate  certain  species  of  organ- 
isms, such  as  the  fungi  of  Penicilium  Glaucum,  Penicilium  Roque- 
fort!, Cladosporium  butyri,  Oidium  lactis,  Actinomycoces  odorifora, 
yeast  and  various  bacterial  species,  such  as  Bacterium  fluorescens, 
Bacterium  prodigiosum,  Bacillus  mesentericus,  etc.,  and  that  these 
species  are  capable  of  making  butter  rancid,  has  led  to  the  conclusion 
that  they  may  be  the  cause  of  rancidity,  either  by  direct  action,  or  by 
the  secretion  of  fat-splitting  enzymes.  It  is,  therefore,  quite  possible 
that  some  of  these  species,  or  similar  groups  of  species,  may  be  in- 
strumental in  developing  rancidity  in  sweetened  condensed  milk.  It 
has  been  further  found  that  the  milk  products  from  certain  indi- 
vidual cows,  or  cows  under  certain  physiological  conditions  are  more 
prone  to  develop  a  rancid  flavor,  than  milk  products  from  other 
cows  or  cows  under  other  conditions. 

Other  agents  capable  of  decomposing  the  glycerides  of  the 
various  fatty  acids,  and  especially  of  oleic  acid,  are  heat,  air  and  light. 
Thus,  sweetened  condensed  milk,  similar  to  butter,  when  exposed  at 
room  temperature  to  light  and  air  will  assume  a  tallowy  and  rancid 
flavor  very  readily.  In  cold  storage  this  development  is  retarded. 
In  the  dark,  it  is  very  slow  and  the  absence  of  air  also  hinders 
this  development. 

Relation  of  Polluted  IVater  to  Rancidity. — Polluted  and  filthy 
water  is  usually  contaminated  with  fungi  and  bacteria  belonging  to 
the  species  enumerated  above  and  which  have  been  found  to  be  able 
to  produce  rancidity.  It  is,  therefore,  not  improbable,  where  such 
water  is  used  in  the  factory  in  the  washing  of  cans,  conveyors, 
kettles,  pipes,  etc.,  in  the  condenser  of  the  vacuum  pan  and  in  the 
cooling  tanks,  as  is  frequently  the  case,  that  the  contamination  of 
milk  with  it  may  result  in  the  development  of  rancidity. 


Condensed  Milk  and  Milk  Powder  163 

Relation  of  Adulterants  to  Rancidity. — It  has  also  been  experi- 
ir.entally  demonstrated  that  the  use,  in  the  process  of  manufacture, 
of  artificial  fats,  or  commercial  glucose  developed  a  distinctly  rancid 
flavor  in  the  finished  product. 

Relation  of  Climate  to  Rancidity. — It  is  frequently  claimed  that 
condensed  whole  milk  shipped  to  the  tropics  turns  rancid,  owing  to 
exposure  of  this  milk,  rich  in  fat,  to  a  warm  climate.  Advantage 
is  sometimes  taken  of  this  argument,  to  justify  violations  of  the  law 
by  skimming  all,  or  a  part  of  the  milk  before  condensing.  This 
matter  has  been  thoroughly  investigated.  All  experimental  results 
show  that  sweetened  condensed  milk,  made  properly  and  in  con- 
formance with  the  law,  and  containing  all  the  butter  fat  of  the 
original  whole  milk,  does  not  turn  rancid  at  any  temperature.  The 
available  evidence  goes  to  show  that  sieges  of  rancid  condensed  milk 
are  usually  the  result  of  the  addition  to  the  product  of  adulterants. 
When,  in  the  manufacture,  nothing  but  pure  milk  from  healthy  cows 
and  the  best  refined  granulated  sucrose  are  used  and  due  attention 
is  given  to  reasonable  cleanliness  in  the  factory,  the  product  is  not 
in  danger  of  becoming  rancid. 

Putrid  Sweetened  Condensed  Milk 

General  Description. — Sweetened  condensed  milk  is  best 
when  fresh.  With  age  it  gradually  develops  a  stale  flavor  which 
frequently  develops  into  a  putrid  odor  and  flavor. 

Causes  and  Pre;vention. — The  purer  the  fresh  milk  and  the 
cane  sugar,  and  the  more  careful  the  processor,  the  longer  will  the 
condensed  milk  retain  its  pleasant  flavor,  provided  that  it  is  stored 
at  a  reasonably  low  temperature.  Age,  however,  will  cause  the  best 
sweetened  condensed  milk  to  become  stale.  The  appearance  of  the 
stale  flavor  is  usually  hastened  when  heating  the  fresh  milk  with 
direct  steam ;  also,  where  the  fresh  milk  is  not  heated  to  a  sufficiently 
high  temperature  (below  176  degrees  F.)  the  condensed  milk  will 
break  down  rapidly  with  age,  usually  developing  a  putrid  flavor  and 
odor.  This  defect  rarely  appears  where  the  fresh  milk  is  heated  to 
180  degrees  F.  or  above.  This  phenomenon  is  probably  due  to  the 
presence  in  milk  of  active  enzymes,  such  as  galactase,  gradually 
decomposing  the  proteids.  The  action  of  most  of  these  enzymes  is 
destroyed  when  the  milk  is  heated  to  176  degrees  F.  or  above. 


164  Condensed  MiIvK  and  Milk  Powder 

Brown  Sweetened  Condensed  Milk 

General  Description. — Some  of  the  sweetened  condensed 
milk  on  tlie  market  has  a  brown  color,  suggesting  chocolate  pudding. 
In  this  condition  it  is  usually  rejected  by  the  consumer. 

Causes  and  Prevention. — All  sweetened  condensed  milk  not 
held  at  a  low  temperature  grows  darker  in  color  with  age.  If  manu- 
factured properly  and  not  exposed  to  unfavorable  conditions,  this 
brown  color  appears  very  gradually  and  not  until  the  condensed 
milk  is  many  months  old.  If  exposed  to  high  temperature  in  storage 
or  transportation,  when  stowed  against  the  boiler  room  in  the  hold 
of  the  steamer,  or  laying  on  the  shelves  of  the  warm  grocery  store 
or  drug  store,  etc.,  it  turns  brown  rapidly.  Condensed  milk  in  cold 
storage  retains  its  natural  color  indefinitely.  Where  milk  is  recon- 
densed  (the  condensed  milk  is  redissolved  either  in  water  or  in. 
fresh  milk  and  condensed  a  second  time),  the  product  is  always 
darker  in  color.  This  brown  color  is  due  to  the  oxidizing  action  of 
heat  on  both,  the  lactose  and  the  sucrose,  a  portion  of  the  sugar 
caramelizing.  Experience  has  shown  that  the  sugar  is  more  sensitive 
to  the  oxidizing  action  of  the  heat  of  recondensing,  than  when  con- 
densed the  first  time. 


CHAPTER  XXIV 

DEFECTIVE  EVAPORATED  MILK  AND  PLAIN 
CONDENSED  BULK  MILK 

The  following  are  the  chief  defects  of  unsweetened  condensed 
milk :  curdy,  grainy,  separated  and  churned,  blown  or  fermented, 
brown,  gritty. 

Curdy,  Plain  Condensed  Milk  and  Evaporated  Milk 

Gener-\l  Description. — Curdy,  unsweetened  condensed  milk 
is  a  term  used  for  milk  in  which  a  part  of  the  casein  is  precipitated 
in  the  form  of  lumps  of  various  sizes.  The  appearance  of  lumps  of 
curd  in  this  product  is  a  defect  that  may  render  the  goods  unsalable. 

Causes  and  Prevention. — Lumps  are  usually  due  to  a  poor 
quality  of  fresh  milk,  the  use  of  excessive  heat  in  the  sterilizing 
process  and  too  high  a  degree  of  concentration. 


Condensed  Milk  and  Milk  Powder  165 

Lumps  in  Plam  Condensed  Bulk  Milk. — Lumps  are  prone  to 
appear  in  plain  condensed  bulk  milk,  as  this  class  of  goods  is  usually 
made  from  fresh  milk  that  may  be  slightly  sour,  as  is  the  case  in 
creameries  and  in  milk  plants  where  the  surplus  and  the  returned 
milk  is  often  manufactured  into  plain  condensed  bulk  milk.  This 
defect  can  be  avoided  by  neutralizing  the  milk  before  heating,  with 
an  alkali  (sodium  bicarbonate  or  lime  water),  heating  less  intensely, 
by  not  carrying  the  condensing  process  quite  so  far,  or  by  overcon- 
densing  before  superheating  and  then  diluting  with  distilled  water  to 
the  proper  density,  after  superheating.  If  the  plain  condensed  bulk 
milk  comes  from  the  pan  in  lumpy  condition,  it  can  usually  be  re- 
duced to  a  smooth  body  by  passing  it  through  an  ice  cream  freezer  at 
ordinary  temperatures. 

Lumps  of  Curd  in  Evaporated  Milk. — The  danger  of  lumpiness, 
or  curdiness  in  evaporated  milk  is  greatly  augmented  by  the  fact 
that,  in  addition  to  the  causes  named  under  plain  condensed  bulk 
milk,  the  sterilizing  process  must  be  dealt  with.  The  high  sterilizing 
temperature  used,  tends  to  precipitate  the  proteids  of  milk,  and  the 
temperature  cannot  be  reduced  below  certain  limits  without  impair- 
ing the  keeping  quality  of  the  product.  Most  of  the  evaporated 
milk,  after  sterilization,  is  subjected  to  the  shaking  process  in  which 
the  coagulum  in  the  cans  is  reduced  to  a  homogeneous  creamy  fluid, 
provided  that  the  curd  is  not  too  hard.  A  curd  will  form  in  the 
sterilizer  in  the  majority  of  cases.  If  it  is  soft  enough,  so  that  it 
can  be  completely  broken  up,  no  harm  is  done.  If  it  is  so  firm  that 
mechanical  shaking  fails  to  cause  it  to  disappear,  then  the  evaporated 
milk  will  reach  the  market  in  lumpy  condition  and  is  difficult  to  sell. 

Effect  of  Quality  of  Fresh  Milk. — ^The  quality  of  fresh  milk  is 
all  important  in  preventing  lumpy  evaporated  milk.  The  milk  must 
come  from  healthy  cows  in  good,  normal  physical  condition.  It  must 
not  contain  colostrum  milk  nor  be  stripper  milk  and  it  must  receive 
the  best  of  care  on  the  farm  and  reach  the  factory  perfectly  sweet. 
Milk  that  is  not  of  high  quality  in  every  respect  should  not  be  re- 
ceived at  the  factory.^ 

Effect  of  Concentration. — The  more  concentrated  the  evaporated 
milk,  the  greater  the  danger  of  lumpiness.  All  the  conditions  caus- 
ing lumpiness  are  intensified  by  the  degree  of  concentration.  The 
manufacturer  must,  therefore,  study  the  behavior  of  his  product  at 


1  For  detailed  discussion  of  relation  of  quality  of  fresh  milk  to  curdiness  of  evaporated 
milk  see  Chapter  VIII  on  "Manufacture  of  Evaporated  Milk,"  "Quality  of  Fresh  Milk." 
p.  81 


i66  Condensed  Milk  and  Milk  Powder 

different  degrees  of  concentration,  and  then  decide  how  much  evap- 
oration it  will  stand  without  developing  subsequently  a  permanent 
curd  in  the  sterilizer.^ 

Effect  of  Sterilisation. — The  coagulum  is  formed  in  the  steril- 
izer. The  higher  the  temperature,  other  conditions  being  the  same, 
the  firmer  the  curd.  The  lowest  temperature  that  will  efficiently 
sterilize  the  evaporated  milk  should,  therefore,  be  used.  Since  the 
sterilizing  temperature  to  be  maintained  cannot  be  modified  below 
certain  limits,  it  is  necessary,  when  the  milk  is  very  sensitive  to 
the  heat,  to  lower  the  degree  of  concentration.  In  some  factories 
fractional  sterilization  is  resorted  to  with  batches  of  milk  that  are 
suspicious.  By  so  doing,  lower  temperatures  can  be  used  eft'ectively. 
but  this  process  calls  for  much  more  labor,  increases  the  cost  of 
manufacture  and  decreases  the  capacity  of  the  factory. 

Effect  of  Fractional  Curdling. — Experience  has  shown  that,  if 
the  proteids  in  evaporated  milk  are  partly  precipitated  by  heat  before 
the  milk  reaches  the  sterilizer,  the  curd,  or  lumps  formed  in  the 
sterilizer  are  less  firm  and  can  be  shaken  out  more  readily.  It  is, 
therefore,  advisable  to  heat  the  milk  in  the  forewarmers  to  as  near 
the  boiling  point  as  possible  and  to  hold  it  at  that  temperature  for  at 
least  five  minutes  before  it  is  drawn  into  the  pan.  The  superheating 
of  the  evaporated  milk  before  it  leaves  the  pan  is  an  additional  safe- 
guard against  the  formation  of  excessive  curd  in  the  sterilizer. 

Effect  of  Homogenizing  Evaporated  Milk. — Excessive  pressure 
in  the  homogenizer  tends  to  so  change  the  physical  properties  of 
the  csfsein  as  to  render  it  more  sensitive  to  the  sterilizing  process. 
Evaporated  milk,  homogenized  under  excessive  pressure  almost 
invariably  forms  a  firm,  unshakable  curd  in  the  sterilizer.  The 
homogenizing  pressure  should  be  kept  down  to  one  thousand  pounds 
or  below. - 

Acid  Fln.v  in  the  Cans  Causes  Lumps. — Similar  as  in  the  case 
of  the  sweetened  condensed  milk,  the  presence  of  acid  flux  in  the 
cans  of  evaporated  milk  causes  lumpiness.  The  acid  that  reaches 
the  interior  of  the  cans  causes  the  milk  coming  in  contact  with  the 
seams  to  curdle.  Only  acid-free  flux  should  be  used  in  the  manufac- 
ture and  sealing  of  the  cans. 


1  For  detailed  discussion  ol  relation  of  concentration  to  curdiness  of  evaporateii  milk 
see  Chapter  IX  on  "Manufacture  of  Evaporated  Milk,"  "Striking,"  p.  83 

2  For  detailed  discussion  of  the  effect  of  homogenizing  on  curdiness  see  Chapter  X  on 
"Homogenizing"  and  Chapter  XXIV  on  "Separated  and  Churned  Evaporated  Milk,"  p.  167 


Condensed  Milk  and  Milk  Powder        '  167 

Grainy  Evaporated  Milk 

General  Description. — This  term  is  sometimes  applied  to 
lumpy  milk,  in  which  case  it  means  the  same.  By  grainy  milk,  how- 
ever, is  generally  understood  milk  which  contains  a  sediment  of  a 
white  granular  appearance,  which  is  insoluble. 

Causes  and  Prevention. — This  granular  sediment  is  largely 
found  in  the  hermetically  sealed  cans  after  the  sterilizing  process. 
It  is  due  to  excessively  high  sterilizing  temperatures  or  too  long 
exposure  of  the  milk  to  the  process.  It  consists  largely  of  the 
mineral  matter  of  milk,  rendered  insoluble  and  precipitated  by  heat. 
Sometimes  as  much  as  a  teaspoonful  is  found  in  a  i6-ounce  can. 
The  use  of  lower  sterilizing  temperatures  or  the  shortening  of  the 
period  of  sterilization  will  help  to  avoid  this  defect. 

Separated  and  Churned  Evaporated  Milk 

General  Description. — This  is  a  very  common  defect.  A 
portion  of  the  butter  fat  of  the  contents  of  the  hermetically  sealed 
cans,  has  separated  and  appears  in  the  form  of  lumps  of  cream  or  of 
churned  butter,  on  top  of  the  evaporated  milk.  While  this  separated 
evaporated  milk  is  normal  in  quality  and  wholesomeness,  its  appear- 
ance condemns  it. 

Causes  and  Prevention. — As  explained  in  Chapter  X  on 
"Homogenizing,"  p.  85,  the  fundamental  cause  of  separated  and 
churned  evaporated  milk  lies  in  the  difference  of  the  specific  gravity 
between  the  butter  fat  and  the  rest  of  the  milk  constituents.  The 
fat  globules,  being  lighter  than  the  serum,  tend  to  rise  to  the  surface, 
forming  a  layer  of  thick  cream.  When  this  separated  evaporated 
milk  is  subjected  to  agitation,  as  is  the  case  in  transportation,  this 
cream  churns  into  lumps  of  butter.  This  tendency  of  the  fat  to 
separate  in  storage  and  churn  in  transportation,  increases  with  the 
increase  of  the  size  of  the  fat  globules,  because  the  larger  the  glo- 
bules, the  larger  is  their  cubic  content  in  proportion  to  their  surface. 
This  fact  is  based  on  the  well  known  physical  law.  that  the  surfaces 
of  two  spheres  are  to  each  other  as  the  squares  of  their  diameters, 
and  the  cubic  contents  of  two  spheres  are  to  each  other  as  the  cubes 
of  their  diameters.  The  cubic  contents  determine  the  gravity  force, 
or  buoyancy,  while  the  surfaces  control  the  resistance  force.  There- 
fore, the  larger  the  fat  globules  the  greater  is  their  buoyancy  and 


1 68 


Condensed  Milk  and  Milk  Powder 


the  weaker  is  the  relative  resistance  which  they  must  overcome  in 
their  upward  passage. 

Effect  of  Locality  and  Season. — Since  the  predominating  size 
of  fat  globules  in  milk,  varies  with  breed  and  period  of  lactation  of 
the  cows/  the  ease  with  which  evaporated  milk  separates  and  the 
difficulty  of  overcoming  this  defect,  differ  greatly  with  locality  and 
season  of  year.  The  fat  globules  in  milk  from  the  Channel  Island 
breeds,  average  two  to  three  times  as  large  as  those  in  milk  from  the 
Holsteins  and  Ayrshires.  Therefore,  factories  located  in  Holstein 
and  Ayrshire  territories  are  not  troubled  nearly  as  much  with  fat 
separation  in  evaporated  milk,  as  factories  in  localities  where  Jerseys 
and  Guernseys  predominate. 

Again,  the  fat'  globules  are  largest  at  the  beginning  of  the 
period  of  lactation  and  decrease  in  size  as  the  period  of  lactation 
advances. 


Relation  of  Breed  and  Period  of  Lactation  to  Size  of  Fat  Globules^ 


Months   of   period 
of  lactation 

Breeds  of  dairy  cows 

Jersey 
25  cows 

Guernsey 
20  cows 

Holstein 
9  cows 

Ayrshire 
33  cows 

Holdemess 
20  cows 

Devon 
16  cows 

1104 
1098 
1228 
1097 
1149 
846 
1017 
733 
715 
571 

928 
1063 
954 

7.37 
584 
568 
408 
426 

640 
576 
256 
396 

595 
341) 
310 

384 

284 

687 
580 
624 
426 
384 
399 
.322 
298 
241 
248 

661 
637 
501 
397 
324 
329 
379 
315 
336 

546 

2nd 

585 

3rd 

i 

450 

4th 

> 

547 

5th 

319 

6th 

> 

355 

7th 

< 

270 

8th 

t 

20) 

9th 

< 

250 

( 

228 

Aver 

jge  for  year.... 

955.8 

716.6 

420.1 

420.9 

427.  G 

375 

1  Hunziker,    Mills   and   Spitzer,    "Moisture   Control  of  Butter. 
Experiment  Station,  Bulletin  No.  159,  1912,  pp.  330-334 


Indiana  Agricultural 


In  order  to  equalize  the  output  of  evaporated  milk  throughout 
the  year,  condensing  concerns  make  every  effort  to  induce  their 
patrons  to  time  the  breeding  of  their  cows  in  such  a  way  that  the 
fresh  cows  are  distributed  throughout  the  year.  The  result  of  this 
practice  is,  that  the  milk  supply  of  these  factories  represents  at  all 
times  a  mixture  of  milk  from  cows  at  all  stages  of  their  period  of 
lactation.  This  naturally  equalizes  the  behavior  of  the  finished 
product  as  far  as  separation  of  the  fat  is  concerned,  facilitating  the 
control  of  this  separation.     On  the  other  hand,  in  localities  of  fac- 


Condensed  Milk  and  Milk  Powder  169 

tories,  newly  established,  summer  milk  is  largely  produced  and  the 
majority  of  cows  freshen  in  the  spring.  This  causes  a  marked 
increase  of  the  size  of  the  average  fat  globules  in  early  summer, 
rendering  the  manufacture  of  evaporated  milk,  that  does  not  sepa- 
rate its  fat,  more  difficult. 

Effect  of  Degree  of  Concentration. — Other  conditions  being  the 
same,  the  more  concentrated  the  product  the  less  the  danger  of  fat 
separation  in  the  finished  product.  The  reason  for  this  lies  in  the 
fact  that  with  the  concentration  the  viscosity  and  the  resistance  force 
of  the  evaporated  milk  increase,  hindering  the  fat  globules  in  their 
upwarci  passage.  This  is  partly  offset  by  the  increase  in  the  specific 
gravity  of  the  product,  but  the  increase  of  the  resistance  force  exerts 
a  stronger  influence  against  separation  of  the  fat,  than  the  increase 
of  the  gravity  force  exerts  in  favor  of  fat  separation. 

However,  as  the  concentration  increases,  the  evaporated  milk 
becomes  more  sensitive  to  the  sterilizing  process  and  beyond  certain 
limits  it  would  be  necessary  to  reduce  the  temperature  or  the  length 
of  exposure  to  heat,  or  both,  in  order  to  prevent  the  more  highly 
concentrated  milk  from  becoming  permanently  curdy.  If,  in  order 
to  increase  the  viscosity,  the  degree  of  concentration  is  carried  so 
far  that  the  sterilizing  process  has  to  be  shortened,  nothing  is  gained 
but  much  may  be  lost.  It  is  obvious,  therefore,  that  the  degree  of 
concentration  does  not  furnish  a  practical  basis  for  controlling  fat 
separation. 

Effect  of  the  Sterilising  Process. — Prolonged  exposure  of  the 
evaporated  milk  to  the  sterilizing  heat  tends  to  so  change  the  physical 
properties  of  the  albuminoids,  as  to  render  the  product  more  viscous. 
Within  the  limits  of  the  necessary  sterilizing  heat,  long  exposure  to 
moderate  heat  is  more  effective  in  this  respect  than  short  exposure 
to  a  high  degree  of  heat.  Since  the  greater  viscosity  tends  to  keep 
the  fat  globules  from  rising,  the  use  of  a  prolonged  sterilizing  process, 
in  which  the  heat  is  applied  slowly,  is  more  effective  in  preventing 
fat  separation  in  the  evaporated  milk  than  a  rapid,  short  process,  in 
which  the  temperature  used  is  very  high. 

It  should  be  understood  from  the  discussion  in  previous  chapters 
that,  in  regulating  the  process  of  sterilization,  the  processor  should 
be  governed  by  the  condition  and  behavior  of  the  milk  and  that  on 
the  one  hand  the  degree  and  duration  of  heat  should  always  be  suf- 


170  Condensed  Milk  and  Milk  Powder 

ficient  to  insure  absolute  sterility  of  the  product,  while  on  the  other 
he  must  guard  against  the  formation  of  an  unshakable  curd.^ 

Effect  of  Superheating. — The  viscosity  of  the  evaporated  milk 
may  also  be  slightly  increased  and  its  sensitiveness  towards  the 
sterilizing  heat  lessened  by  superheating  it  in  the  vacuum  pan. 

Turning  the  Cans  in  Storage. — Many  manufacturers,  in  an 
efifort  to  avoid  fat  separation,  have  adopted  the  practice  of  turning 
their  goods  in  storage  at  regular  intervals.  This  operation  naturally 
interferes  with  and  retards  the  rising  of  the  fat  to  the  surface,  as 
l®ng  as  the  goods  remain  in  the  factory.  After  they  leave  the  factory 
this  control  must  of  necessity  cease  and  if  the  evaporated  milk, 
owing  to  the  process  of  manufacture  and  the  condition  of  the 
product,  is  destined  to  separate  its  fat,  the  turning  of  the  cases, 
while  at  the  factory,  cannot  permanently  prevent  separation.  Where 
the  goods  are  consumed  immediately  after  they  leave  the  factory, 
this  practice  may  serve  the  purpose ;  but,  since  the  large  bulk  of 
evaporated  milk  manufactured,  is  exposed  to  prolonged  storage,  its 
advantage  is  very  limited. 

Effect  of  Homogenizing. — Under  average  conditions  careful 
attention  to  the  precautions  above  discussed  will  greatly  minimize 
and  often  prevent  fat  separation.  At  best,  however,  much  of  the 
evaporated  milk  on  the  market  shows  signs  of  separation  after  sixty 
to  ninety  days  and  some  of  it  even  after  two  weeks,  for  the  funda- 
mental cause  of  separation,  the  difference  in  gravity  between  the 
fat  globules  and  the  rest  of  the  milk  constituents,  is  still  present; 
then  again,  under  less  favorable  conditions,  even  the  above  precau- 
tions may  not  prove  adequate  to  keep  the  fat  from  separating. 

The  introduction  of  any  agent  or  process,  therefore,  capable  of 
permanently  removing  this  fundamental  cause,  must  prove  a  lasting 
benefit  to  the  manufacturer  of  evaporated  milk.  This  agent  hah 
been  found  in  the  homogenizer.  The  homogenizer  makes  it  possible 
to  divide  the  fat  globules  so  finely,  that  their  buoyancy  or  gravity 
force  is  not  great  enough  to  overcome  the  resistance  of  the  sur- 
rounding liquid.  They  are  unable  to  rise  to  the  surface,  but  remain 
in  homogeneous  emulsion. 

The  chief  objection  to  the  use  of  the  homogenizer  is  its  effect 
on  the  casein  of  the  milk.     Beyond  certain  limits  of  pressure  it  so 


For  detailed  discussion  see  Chapter  XII  on  "Sterilizing,"  p. 


Condensed  Miek  and  Miek  Powder  171 

affects  the  casein,  that  the  latter  is  more  prone  to  curdle  in  the 
sterilizer.  However,  experience  has  amply  shown  that  the  maximum 
pressure  required  to  prevent  fat  separation  in  the  finished  product, 
is  not  great  enough  to  seriously  affect  the  behavior  of  the  casein 
during  sterilization.  Hence,  the  proper  regulation  of  the  pressure 
and  the  intelligent  use  of  the  homogenizer,  furnish  a  satisfactory 
and  reliable  means  to  prevent  fat  separation.  Under  average  con- 
ditions, the  use  of  sufficient  pressure  to  reduce  the  fat  globules  to 
one-third  of  their  original  size,  practically  destroys  the  power  of  the 
fat  globules  to  rise  to  the  surface.  A  pressure  of  approximately 
one  thousand  pounds  per  square  inch,  makes  possible  this  reduction 
of  the  size  of  the  fat  globules.^ 

Fermented  Evaporated  Milk 

Generae  Description. — Fermented  evaporated  milk  is  evap- 
orated milk,  which  after  sterilization,  has  undergone  fermentation. 
The  type  of  fermentations  found  in  this  product  varies  with  locality, 
season  of  year  and  factory  conditions.  The  contents  of  the  cans 
may  have  soured  with  curd  formation,  or  a  curd  may  have  formed 
without  acid  development,  or  the  fermentation  may  be  gaseous,  in 
which  case  the  cans  bulge,  and  these  gaseous  fermentations  may  be 
accompanied  by  acid  formation  or  by  putrefactive  products.  In  all 
cases  of  fermented  milk  the  product  is  entirely  worthless.  These 
defects  are  usually,  though  not  always,  detected  during  the  period 
of  incubation. 

Fermented  evaporated  milk  is  the  result,  either  of  incomplete 
sterilization,  or  of  leaky  cans.  The  causes  of  fermented  evaporated 
milk  differ  with  the  specific  type  of  fermentations  produced;  they 
will  be  discussed  separately  and  as  relating  to  the  respective  types 
of  fermentations. 

Acid  Fermentation,  Sour,  Curdled,  Evaporated  Milk 

General  Description. — Upon  opening  the  cans  the  contents 
are  found  to  be  sour  and  curdy. 

Causes  and  Prevention. — This  condition  is  the  result  of  the 
presence  of  acid  producing  species  of  micro-organisms,  usually  of 
the  lactic  acid  type,  which  sour  the  milk,  and  the  acid  produced 
curdles  the  casein.     Since  the  majority  of  the  lactic  acid  bacteria 


For  details  on  the  use  of  homogenizer  see  Chapter  X  on  "Homogenizing,"  p.  85 


172  Condensed  Milk  and  Milk  Powder 

are  not  resistant  to  heat  and  "are  destroyed  at  relatively  low  heat, 
this  defect  is  not  usually  caused  by  incomplete  sterilization.  The 
temperature  of  sterilization,  though  it  might  be  insufficient  to  kill 
spore  forms,  is  high  enough  to  make  it  impossible  for  lactic  acid 
bacteria  to  pass  the  process  alive. 

The  only  way  in  which  this  defect  can  occur  is  through  subse- 
quent contamination  of  the  contents  of  the  cans  with  these  germs, 
and  the  only  possible  channel,  through  which  this  subsequent  con- 
tamination may  occur,  is  leaky  cans,  or  leaky  seals.  A  careful 
examination  of  the  cans  of  sour,  curdled  evaporated  milk  usually 
shows  faulty  cans  or  faulty  seals. 

Bitter  Curd 

General  Description. — When  the  cans  are  opened  the  con- 
tents present  a  solid  coagulum,  generally  noticeably  white  in  color 
and  very  bitter  to  the  taste,  similar  to  the  bitterness  of  dandelions. 
There  is  a  separation  of  practically  clear  whey,  the  curd  does  not 
break  down  readily  upon  shaking  and  the  acid  reaction  of  the  mix- 
ture of  curd  and  whey  is  about  .35  to  .40  per  cent.,  which  is  normal 
for  evaporated  milk. 

Causes  and  Prevention. — Microscopic  examinations  under 
high  magnification  of  cultures  in  sterile  milk  show  the  presence  of 
very  small  bacilli.  The  milk  forms  a  firm  coagulum  in  five  to  seven 
days  and  when  over  one  week  old  the  curd  has  the  same  strong, 
bitter  taste  as  that  in  the  cans.  The  bitterness  increases  with  age. 
These  bacilli  grow  best  at  90  degrees  F.  They  are  facultative  anae- 
robes, developing  both,  in  aerobic  and  anaerobic  media,  but  prefer 
anaerobic  conditions. 

In  the  cases  under  observation  no  spores  were  detected  and 
exposure  for  fifteen  minutes  to  212  degrees  F.  destroyed  these  germs. 
The  above  findings  do  not  exclude  the  possibility  of  spore  formation 
under  conditions  very  unfavorable  to  growth  and  life. 

The  presence  of  this  species  of  bitter  curd  organisms  suggests 
incomplete  sterilization  of  the  evaporated  milk.  The  striking  white- 
ness of  the  curd  in  all  cases  that  have  come  to  the  writer's  attention, 
is  further  proof  of  the  correctness  of  this  deduction.  It  indicates 
that  these  cans  received  relatively  little  heat  in  the  sterilizer,  other- 
wise the  curd  would  have  a  darker  color.  This  defect  usually  does 
not  show  up  in  all  the  cans  of  one  and  the  same  batch,  but  only  in  a 


Condensed  Milk  and  Milk  Powder  173 

limited  portion  of  each  batch.  This  fact  suggests  that  the  distribu- 
tion of  heat  in  the  sterihzer  is  not  uniform,  some  cans  getting  less 
heat  than  others. 

This  defect  occurs  generally  in  summer,  a  fact  which  may  be 
due  to  one  or  both  of  the  following  conditions: 

While  it  is  well  known  that  there  is  a  variety  of  species  of  bac- 
teria, yeast  and  torula  that  are  capable  of  producing  a  bitter  curd, 
either  direct,  or  through  the  secretion  of  casein-curdling  en'zymes, 
and  while  these  different  species  of  micro-organisms  come  from  a 
variety  of  sources,  the  most  common  sources  are,  the  soil,  pasture. 
water  and  the  udder  itself.  It  is  a  noteworthy  fact  that  this  defect 
is  most  commonly  found  in  milk  and  milk  products  when  the  cows 
are  on  pasture.  It  is,  therefore,  probable  that,  in  most  cases,  this 
troublesome  germ  is  carried  into  the  milk  on  the  farm. 

Again,  in  summer,  at  a  time  when  this  defect  generally  occurs, 
the  effect  on  the  cows  of  the  summer  heat  and  flies,  and  the  ten- 
dency toward  high  acid  in  milk,  render  the  milk  most  sensitive  to 
the  sterilizing  heat.  The  operator  finds  it  difficult  to  avoid  the  for- 
mation of  a  disastrous  curd  in  the  sterilizer.  In  order  to  guard 
against  this  trouble  he  is  tempted  to  either  lower  the  temperature, 
or  shorten  the  duration  of  the  sterilizing  process.  This  tends  to- 
wards incomplete  sterilization.  A  very  frequent  result  of  this  in- 
complete sterilization  in  the  early  summer  months,  is  the  formation 
of  a  bitter  curd.  When  the  processor  returns  to  the  proper  sterili- 
zing process,  the  occurrence  of  bitter  curd  in  the  cans  disappears 
and  the  product  is  normal. 

A  further  safeguard  against  the  recurrence  of  this  trouble  lies 
in  providing  for  uniform  distribution  of  heat  in  the  sterilizer.  If 
the  cans  have  to  be  stacked  in  deep  tiers,  which  is  undesirable  and 
.should  be  avoided,  slats  of  wood  or  iron  should  be  placed  over  the 
top  of  every  second  row  of  cans.  This  will  make  possible  the  free 
access  of  steam  to  at  least  one  end  of  each  can.  If  the  circulation 
of  steam  in  the  sterilizer  is  poor,  the  uniform  distribution  of  heat 
can  be  facilitated  by  filling  the  sterilizer  about  one-third  full  of  water 
so  that,  with  every  revolution  of  the  frame-work,  the  cans  have  to 
pass  through  this  water  once.  The  water  reaches  every  nook  in  the 
interior  of  the  sterilizer,  distributing  the  heat  much  more  uniformly 


174 


Condensed  Milk  and  Milk  Powder 


than  the  steam.  If  these  precautions  fail  to  remedy  the  trouble,  then 
the  entire  process  is  inadequate  and  either  more  heat,  or  longer  ex- 
posure to  the  same  heat  is  necessary. 

It  is  obviously  imperative  that  the  fresh  milk,  as  it  arrives  at 
the  factory,  be  subjected  to  the  most  rigid  inspection  on  the  plat- 
form, in  order  to  guard  against  the  processing  of  unduly  contam- 
inated milk. 

Blown  Evaporated  Milk  (Gaseous  Fermentation) 

General  Description. — The  ends  of  the  cans  bulge  out  very 
noticeably,  frequently  so  much  so  that  the  seams  of  the  cans  burst 
open.  This  is  due  to  gaseous  fermentation  causing  high  pressure  in 
the  cans.  The  pressure  is  often  so  great,  that  upon  opening  the  cans, 
most  of  the  contents  are  blown  out  with  tremendous  force.  In  some 
cases  of  blown  evaporated  milk,  the  contents  have  an  acid  odor, 
pleasant  and  aromatic.  In  most  instances,  however,  they  give  oflf 
very  foul  odors  and  suggesting  hydrogen  sulfide,  not  unlike  ag- 
gravated cases  of  Limburger  cheese.  These  odors  are  exceedingly 
penetrating  and  difficult  to  remove  from  anything  they  come  in  con- 
tact with. 

Causes  and  Prevention. — The  bacteria  causing  gaseous  fer- 
mentations in  evaporated  milk  usually  belong  to  the  anaerobic  group 
of  butyric  acid  species  and  in  most  cases,  though  not  always,  the 
putrefactive  types  prevail,  such  as  Bacillus  putrificus,  Plectridium 
novum  and  Plectridium  foetidum,  especially  the  latter,  because  of  its 
extraordinary  power  of  resistance  to  heat.  Plectridium  foetidum  is 
an  obligatory  anaerobe  and  it  absolutely  refuses  to  grow  under 
aerobic  conditions.  It  is  an  actively  motile,  medium-sized  organism 
with  flagella  and  spores.  At  one  end  it  has  an  Indian  club-like  en- 
largement, in  which  appears  the  spore.  The  bacillus  resembles  a 
kettle-drum  stick  similar  to  B.  tetani.  Under  strictly  anaerobic  con- 
ditions, and  incubated  at  90  degrees  F.,  it  ferments  milk  in  four  days. 
The  milk  first  curdles,  then  gradually  the  curd  dissolves  (digests) 
completely,  leaving  a  clear  yellow  liquid,  similar  in  appearance  to 
butter  oil.  The  fermentation  is  accompanied  by  the  evolution  of  a 
penetrating  foul  odor.  This  organism  survives  cx]:)osure  for  15 
minutes  to  245  degrees  F.  Its  thermal  death  point  lies  between  245 
and  250  degrees  F. 


Condensed  Milk  and  Milk  Powder  175 

Plectridium  foetidum,  as  well  as  most  of  the  other  species  of 
anaerobic,  spore  bearing  butyric  acid  bacilli  and  bacteria,  is  present 
abundantly  in  cultivated  soil,  in  field  crops  and  even  on  the  kernels 
of  the  grain.  Since  this  type  of  evaporated  milk  defect  is  charac- 
teristic, especially,  of  the  product  manufactured  during  the  late  sum- 
mer and  early  fall  months,  it  is  very  probable  that  the  dust  incident 
to  the  harvesting  of  the  field  crops,  furnishes  the  chief  source  of 
contamination  of  the  milk. 


c^ss:^ 


V 


^V^ 


r 


<^ 


Figr.    53.       Plectridium    foetidum,    a 
liighly    resistant    species    of   anaerobic 
microorganisms,  causing  "swell  heads" 
Fig.  53.     The  result  of  gaseous  fermentation      of  evaporated  milk 


In  order  to  avoid  the  occurrence  of  blown,  fermented,  evapo- 
rated milk,  therefore,  it  is  necessary  to  employ  the  highest  sterilizing 
temperatures,  or  the  longest  exposure  to  the  sterilizing  heat,  or  both, 
consistent  with  freedom  of  the  milk  from  curdiness.  Experience  has 
shown  that  the  use  of  the  formula  for  sterilizing,  given  under  Chap- 
ter XII  on  "Sterilizing,"  guards  effectively  against  this  defect. 

Blown  Evaporated  Milk  Due  to  Freezing. — If  the  evaporated 
milk  is  exposed  to  storage  temperatures  below  the  freezing  point 
of  water,  the  contents  of  the  cans  will  freeze.  While  freezing,  the 
contents  expand  sufficiently  to  cause  the  ends  of  the  cans  to  bulge. 
When  the  cans  are  subsequently  transferred  to  warmer  temper- 
atures, so  that  their  contents  melt  'again,  the  milk  contracts  and  the 
cans  resume  their  normal  shape. 

While  the  wholesomeness  and  flavor  of  the  product  are  not  af- 
fected by  the  freezing  process,  the  remelted  evaporated  milk  is  usu- 
ally less  smooth  and  often  slightly  grainy.     This  is  due  to  the  fact 


176  Condensed  Milk  and  Milk  Powder 

that,  during  the  process  of  freezing,  there  is  a  partial  separation  of 
the  watery  portion  from  the  caseous  material.  The  casein  contracts 
and  the  watery  portion  freezes.  When  melted,  the  emulsion  is  less 
complete  than  it  was  before  freezing.  The  casein  remains  in  its  con- 
tracted form  and  robs  the  product  of  its  original  smoothness. 

Blown  Evaporated  Milk  Due  to  Chemical  Action. — While  prop- 
erly processed  evaporated  milk  is  perfectly  sterile,  and  from  the 
biological  point  of  view,  keeps  indefinitely,  the  cans  of  very  old, 
evaporated  milk  may  bulge,  as  the  result  of  the  action  of  the  acid 
in  the  milk  on  the  container.  Evaporated  milk  contains  from  .35 
to  .50  per  cent,  acid  (calculated  as  lactic  acid).  When  the  tin  cans 
are  filled  with  the  evaporated  milk,  the  tinplate  is  bright  and  untarn- 
ished, both,  inside  and  out.  After  the  sterilizing  process,  the  inside 
surface  of  the  cans  is  dark  and  dull.  This  is  caused  by  the  com- 
bined action  of  acid  and  heat,  which  seems  to  weaken  the  tinplate. 
This  phenomenon  is  further  illustrated  by  the  fact  that  where  cream- 
eries pasteurize  their  skimmilk  and  return  it  to  the  patrons  in  the 
milk  cans  hot,  the  milk  cans  are  short-lived ;  they  soon  corrode  and 
begin  to  leak. 

The  acid  in  the  evaporated  milk  continues  to  act  on  the  tin- 
plate  of  the  can  after  manufacture  and  in  the  case  of  very  old 
evaporated  milk,  the  acid  may  decompose  a  considerable  part  of  the 
iron.  This  action  is  accompanied  by  the  evolution  of  hydrogen  gas, 
which  causes  the  cans  to  bulge.  This  action  is  hastened  by  con- 
tinued exposure  of  the  goods  to  high  temperatures  (summer  heat). 
This  fact  was  experimentally  demonstrated,^  also,  by  scratching 
the  bottom  of  tin  cans  on  the  inside  with  a  file,  then  filling  the  cans 
with  a  .4  per  cent,  solution  of  'lactic  acid  and  acetic  acid,  respec- 
tively. After  sealing,  the  cans  were  sterilised  in  the  autoclave,  so 
as  to  avoid  any  possibility  of  bacterial  action'.  After  cooling,  these 
sterilized  cans  were  incubated  for  some  time  at  90  degrees  F.  The 
cans  containing  the  dilute  acid  began  to  swell,  while  the  check  cans, 
containing  distilled  water  only,  remained  normal. 

Brown  Evaporated  Milk 

General  Description. — It  is  the  aim  of  the  processor  to  so 
govern  the  sterilizing  process  as  to  give  the  evaporated  milk  a  rich. 


Hunziker  and  Wright,  Indiana  Agricultural  Experiment  Station.    Results  not  published 


Condensed  Milk  and  Milk  Powder  177 

yellow,  creamy  color.  Frequently,  this  color  limit  is  overstepped 
to  the  extent  of  imparting  to  the  evaporated  milk  a  brown  color, 
suggesting  coffee  jvith  milk  in  it.  In  this  condition  evaporated  milk 
fails  to  appeal  to  the  consumer. 

Causes  and  Prevention. — The  dark  color  in  evaporated  milk 
is  due  to  the  oxidizing  action  of  excessive  heat  on  the  milk  sugar, 
causing  the  milk  sugar  to  caramelize.  This  can  be  avoided  by  re- 
ducing the  sterilizing  temperature,  or  shortening  the  sterilizing 
process,  or  both.  The  storing  of  evaporated  milk  at  high  temper- 
atures (summer  heat)  also  tends  to  deepen  its  color  with  age. 

Gritty  Plain  Condensed  Bulk  Milk 

General  Description. — Grittiness  in  the  unsweetened  goods 
appears  usually  only  in  the  plain  coudensed  bulk  milk.  It  is  a 
defect  which  renders  the  product  undesirable  for  ice  cream  making. 

Causes  and  Prevention. — The  chief  cause  of  this' defect  is 
too  great  concentration.  Plain  condensed  bulk  milk  which  is  not 
condensed  over  3.5  parts  of  fresh  milk  to  i  part  of  condensed  milk 
does  not  become  gritty.  When  the  concentration  exceeds  4:1,  the 
milk  sugar  begins  to  crystallize  out,  making  the  product  gritty. 
Milk  sugar  requires  about  six  times  its  weight  of  water  for  com- 
plete solution  in  cold  water.  When  condensed  at  the  ratio  of  4:1 
or  over,  the  plain  condensed  bulk  milk  contains  considerably  less 
than  five  parts,  by  weight,  of  water  to  one  part  of  milk  sugar.  This 
high  concentration,  together  with  the  practice  of  storing  this  product 
at  refrigerating  temperatures  in  order  to  preserve  it,  is  responsible 
for  the  grittiness.  This  trouble  can,  therefore,  easily  be  prevented 
by  not  condensing  to  quite  as  high  a  degree  of  concentration. 


CHAPTER  XXV 
ADULTERATIONS  OF  CONDENSED  MILK 

It  is  the  sense  of  the  Federal  Pure  Food  Act  that  the  addition 
to  condensed  milk  of  any  substance  except  sucrose,  and  the  ab- 
straction of  any  substance  from  milk  except  water,  is  an  adulter- 
ation. 

Skimming. — Condensed  milk  made  from  partly  or  wholly 
skimmed  milk  must  be  labeled  and  sold  as  condensed  skimmed  milk 


178  Condensed  Milk  and  Milk  Powder 

ill  order  to  comply  with  the  Pure  Food  regulations.  However,  it 
is  possible  for  condenseries  receiving  fresh  milk,  rich  in  butter  fat, 
to  skim  a  part  of  that  milk  and  have  their  product  still  conform 
with  the  food  standards. 

Skimmed  sweetened  condensed  milk  can  readily  be  detected  by 
its  whitish  color,  while  condensed  whole  milk  has  normally  a  rich 
yellow  color.  When  diluted,  to  the  consistency  of  ordinary  milk, 
skimmed  condensed  milk,  both  the  sweetened  and  the  unsweetened, 
foams  very  profusely  when  shaken,  while  diluted  condensed  whole 
milk  behaves  similar  to  ordinary  whole  milk.^ 

Addition  of  Artificial  Fats. — In  order  to  lower  the  cost  of 
manufacture,  attempts  have  occasionally  been  made  to  skim  the 
fresh  milk  and  substitute  the  abstracted  fat  by  artificial  fats  of 
animal  or  vegetable  origin.  If  the  punishment  for  such  violations 
of  the  law  and  the  protection  of  the  consumer  had  to  solely  depend 
on  the  findings  of  food  chemists,  justice  would  indeed  be  dealt  out 
verv  slowly,  for  condensed  milk  is  analyzed  for  the  kinds  of  fat 
it  contains  in  but  very  rare  cases,  and  the  detection  of  artificial  fat 
by  chemical  analysis  is  a  difficult  process.  Fortunately  for  the 
consumer,  there  are  easier  and  simpler  means  to  detect  "filled" 
condensed  milk.  The  presence  of  foreign  fats  in  condensed  milk, 
whether  animal  or  vegetable,  give  the  product  a  peculiar  flavor  and 
odor,  not  present  in  the  unadulterated  milk.  This  unnatural  flavor 
and  odor  is  especially  noticeable  when  a  teaspoon ful  of  the  con- 
densed milk  is  dissolved  in  half  of  a  cupful  of  hot  water  or  coffee. 

The  addition  to  condensed  milk  of  artificial  fats  produces  an 
inferior  quality  of  condensed  milk  and  decreases  its  keeping  quality. 
The  milk  is  prone  to  become  rancid.  Condenseries  are  known  to 
have  lost  their  output  of  an  entire  season  as  the  result  of  the 
adulteration  of  their  product  with  artificial  fats.  The  practice  of 
adulterating  condensed  milk  with  foreign  fats  is  now  an  exceed- 
ingly rare  occurrence. 

Addition  of  Commercial  Glucose. — Commercial  glucose  belongs 
to  a  group  of  starch  products  in  which  dextrose  is  the  leading 
constituent.  It  is  manufactured  by  the  action  of  dilute  acids  on 
starch  and  starchy  matter,  or  occasionally  woody  fiber.  In  this 
countrv  it  is  almost  wholly  made  from  maize  starch. 


For  chemical  tests  of  butterfat  in  condensed  milk,  see  Chapter  XXVII 


Condensed  Milk  and  Milk  Powder  179 

Starch  glucose  occurs  in  commerce  in  several  forms,  varying 
from  the  condition  of  pure  anhydrous  dextrose,  through  inferior 
kinds  of  solid  sugar,  to  the  condition  of  a  thick  syrupy  liquid,  col- 
orless and  transparent,  resembling  molasses  in  consistency  and  gly- 
cerine in  appearance ;  it  contains  a  large  proportion  of  dextrin.  In 
connection  with  the  manufacture  of  condensed  milk  the  term  "glu- 
cose" refers  to  this  thick,  syrupy  liquid.  It  is  added  to  the  con- 
densed milk  with  a  view  of  substituting  a  portion  of  the  sucrose 
and  thus  reducing  the  cost  of  manufacture.  It  has  also  been  sug- 
gested that  the  presence  of  commercial  glucose  in  condensed  milk 
prevents  the  precipitation  of  sugar  crystals.  Experiments  have 
shown,  however,  that  condensed  milk  containing  varying  amounts 
of  glucose,  will  become  sandy  just  as  readily  as  normal  condensed 
milk. 

That  glucose  cannot  be  used  as  a  substitute  for  sucrose,  is 
obvious  from  the  fact  that  its  presence  defeats  the  very  object  for 
which  sucrose  is  added.  Instead  of  serving  as  a  preservative,  as 
is  the  case  with  the  best  refined,  granulated  cane  sugar,  glucose  acts 
as  a  most  effective  fermentative.  It  has  been  explained  that  the 
presence  in  sucrose  of  traces  of  invert  sugar,  or  levulose  and  glu- 
cose, causes  condensed  milk  to  ferment.  Glucose  belongs  to  the 
monosaccharides.  Its  chemical  formula,  like  that  of  levulose,  is 
CgH^oOc,.  it  oxidizes  readily  and  under  the  influence  of  yeast  and 
other  micro-organisms  it  ferments,  yielding  mainly  alcohol  and 
carbon  dioxide.  Its  presence  in  condensed  milk,  therefore,  is  prone 
to  start  fermentation,  and  the  manufacturer  who  uses  it  with  a 
view  of  lessening  the  cost  of  manufacture  of  condensed  milk  is, 
indeed,  practicing  poor  economy.  There  is  no  adulteration  of 
sweetened  condensed  milk,  that  will  produce  such  inevitable  dis- 
aster, as  the  addition  to  it  of  glucose.  Aside  from  this  fact,  the  law 
prohibits  the  addition  of  anything  except  sucrose. 

Addition  of  Bi-Carbonate  of  Soda,  Ammonium  Hydroxide, 
Lime  Water  and  Other  Alkali. — ^These  alkalies  are  frequently  added 
to  a  poor  (luality  of  fresh  milk,  for  the  purpose  of  neutralizing  the 
excess  of  acid  and  preventing  the  milk  from  curdling  when  ex- 
posed to  heat.  If  used  in  reasonable  c^uantities,  they  interfere  in 
no  way  with  the  quality  and  healthfulness  of  the  product,  and  may 
in  exceptional  cases,  prevent  great  loss.     If  used  in  excess,  the  milk 


i8o  Condensed  Miek  and  Miek  Powder 

will  foam  very  badly  in  the  vacuum  pan,  which  renders  the  process 
of  condensing  a  difficult  one  and  the  finished  product  has  a  bitter 
flavor.  Under  ordinary  conditions,  their  use  is  entirely  unneces- 
sary and  simply  means  additional  labor  and  expense.  The  above 
agents  and  also  viscogen,  are  sometimes  used  with  the  view  of 
thickening  the  product  and  increasing  the  output.  Experimental 
results,^  however,  showed  that  these  agents  cannot  be  used  in  large 
enough  quantities  to  produce  the  above  results  without  materially 
lowering  the  quality  of  the  product. 

Addition  of  Cream  of  Tartar. — Cream  of  tartar  is  used  ex- 
tensively in  the  manufacture  of  candies  and  caramels.  Its  purpose 
is  to  make  the  sugar  in  these  products  precipitate  in  the  form  of 
very  fine  and  soft  crystals.  Condenseries,  which  have  been  con- 
tinually troubled  with  sugar  crystallization  and  sugar  sediment,  have 
tried  to  overcome  this  defect  by  adding  cream  of  tartar  to  the 
sweetened  milk  in  the  vacuum  pan.  Cream  of  tartar  is  an  acid 
salt  (acid  potassium  tartrate,  KH.C^H^Oq ) ,  and  it  is  this  acid, 
which  in  the  manufacture  of-  candy,  causes  the  fine  and  soft  grain 
of  the  sugar.  It  is  obvious,  that  if  enough  cream  of  tartar  were 
added  to  condensed  milk,  to  produce  the  desired  effect  on  the  sugar, 
the  acid  present  would  curdle  the  milk.  Its  use  is  of  no  value  to 
the  manufacturer  of  condensed  milk. 

Addition  of  Starch. — The  pasty  and  thick  consistency  of  sweet- 
ened condensed  milk  frequently  suggests  to  the  public  that  it  con- 
tains starch.  This  is  erroneous,  for  it  is  doubtful  if  condensed 
milk  is  ever  adulterated  with  starch.  There  would  be  absolutely 
nothing  gained  by  so  doing,  and  the  presence  of  starch  in  condensed 
milk  could  be  readily  detected  with  iodine.  Iodine  gives  the  starch 
cells  a  deep  blue  color. 


Himziker.    Experiiiient8  not  published 


Condensed  Milk  and  Milk  Powder  i8i 


PART    VII 

MANUFACTURE  OF  MILK  POWDER 

CHAPTER  XXVI 

DEFINITION 

Milk  powder,  dry  milk,  pulverized  milk,  dehydrated  milk,  des- 
iccated milk,  is  made  from  cow's  whole  milk,  or  partly  or 
wholly  skimmed  milk,  to  which  sugar,  or  alkalies,  or  both  may,  or  may 
not  have  been  added,  and  which  has  been  evaporated  to  dryness, 
either  under  atmospheric  pressure,  or  in  vacuo. 

KINDS 

The  milk  powders  on  the  market  vary  chiefly  in  their  solu- 
bility and  fat  content.  The  bulk  of  the  milk  powders  is  produced 
from  wholly  or  partly  skimmed  milk.  Most  of  the  milk  powders  of 
the  early  days  of  this  industry,  contained  added  cane  sugar  and 
alkalies.  The  purpose  of  the  addition  of  alkalies  was  to  lend  great- 
er solubility  to  the  proteids. 

The  process  of  manufacture,  however,  has  been  improved  to 
the  extent  to  where  the  solubility  of  the  proteids  can  be  preserved 
without  the  admixture  of  alkalies.  Most  of  the  milk  powders  put 
on  the  market  in  this  country  are  free  from  admixture  of  any  sub- 
stances foreign  to  normal  milk. 

HISTORY  AND  DEVELOPMENT  OF  INDUSTRY 

■  The  origin  and  history  of  the  milk  powder  industry  are  very 
closely  related  and  intimately  connected  with  that  of  the  con- 
densed milk  industry.  The  fundamental  purpose  of  the  two  prod- 
ucts is  one  and  the  same,  i.  e.,  to  preserve  milk  as  nearly  as  possible 
in  its  natural  condition,  and  to  reduce  its  bulk  to  the  minimum,  so  as 
to  make  possible  its  economical  transportation  to  all  parts  of  the 
world. 


i82  Condensed  Milk  and  Milk  Powder 

The  difference  between  milk  powder  and  condensed  milk,  is 
mainly  one  of  degree  of  concentration.  It  is  not  surprising,  there- 
fore, that  the  inventions  of  processes  of  manufacture  of  the  two 
products  date  back  to  about  the  same  period,  the  middle  of  last 
century,  and  in  most  cases,  the  inventors  of  the  one  product  had 
also  in  mind  and  gave  due  consideration  to  the  possibilities  of  the 
other. 

The  first  commercially  usable  process  was  invented  by  Grim- 
wade  who  secured  the  English  patent  in  1855.  His  process  con- 
sisted briefly  of  first  adding  carbonate  of  soda  or  potash  to  the  fresh 
milk,  then  evaporating  in  open  jacketed  pans  and  with  constant 
agitation,  until  a  dough-like  substance  was  obtained ;  then  adding 
cane  sugar;  the  mixture  was  then  pressed  between  rollers  into  rib- 
bons, further  dried  and  then  pulverized.  The  alkali,  in  the  form  of 
carbonate  of  soda  or  potash,  was  added  in  order  to  render  the  casein 
more  soluble,  and  the  purpose  of  the  admixture  of  the  sugar  was  to 
produce  granulation  of  the  dough  toward  the  end  of  the  process. 
The  evaporation  in  open  pans  was  later  .superceded  by  the  use  of 
the  vacuum  pan.  The  Cirimwade  process  of  manufacturing  milk 
powder  was  in  practice  for  some  years. 

The  introduction  and  rapid  development  of  the  condensed 
milk  industry  and  the  difficulty  of  the  economic  manufacture  of  a 
marketable  milk  powder  of  good  keeping  quality,  had  a  retarding 
effect  on  the  development  of  the  milk  powder  industry.  While  oc- 
casional new  processes  were  invented  and  new  patents  granted,  the 
commercial  development  of  the  industry  dates  back  only  about  fif- 
teen to  twenty  years.  Within  the  last  decade  the  industry  in  this 
country  and  in  Europe  has  been  growing  rapidly.  Today  there  are 
in  operation  in  the  United  States  .some  thirty  milk  powder  factories. 

The  bulk  of  the  milk  powder  manufactured  now  is  made  from 
skimmed  milk.  The  manufacture  of  whole  milk  powder  is  as  yet 
very  limited  and  is  confined  to  the  filling  of  specific  orders  for  the 
same,  because  of  its  low  keeping  quality.  The  fact  that  whole  milk 
powder  becomes  rancid  under  similar  conditions,  as  is  the  case  with 
butter,  and  that  it  must  be  refrigerated  in  order  to  keep,  is  over- 
shadowing the  many  and  distinct  advantages  of  this  concentrated 
product.  Until  this  obstacle  is  removed  and  the  manufacturer  is 
able  to  put  on  the  market  a  whole  milk  powder  that  has  the  desired 
keeping  properties,  the  development  of  this  industry  cannot  reach 


Condensed  Milk  and  Milk  Powder 


183 


the  proportions  justifiable  by  the  great  usefulness  of  this  valuable 
product  and  comparable  with  the  manufacture  of  other  forms  oi 
preserved  milk  and  dairy  products. 

QUALITY  OF  FRESH  MILK 

What  has  been  stated  concerning  the  necessity  of  a  high  quality 
of  fresh  milk  in  the  successful  manufacture  of  condensed  milk,  is 
equally  true  in  the  manufacture  of  milk  powder.  The  fresh  milk 
must  be  normal  in  its  properties.  It  must  be  produced  under 
strictly  sanitary  conditions  and  receive  the  proper  care  on  the  farm. 
It  is  especially  essential  that  it  arrive  at  the  factory  perfectly  sweet, 
since  acidity  tends  to  lower  the  solubility  of  the  finished  product. 


DESCRIPTION  OF  THE  PRINCIPAL  PROCESSES  OF 
MANUFACTURE 

Numerous  processes  for  the  manufacture  of  milk  powder  have 
been  invented  and  patented  in  this  country  and  in  Europe.  Many 
of  these  processes  dififer  but  slightly  from  one  another.  For  con- 
venience' sake  these  processes  are  herein  classified  in  accordance 
with  "the  fundamental  principles  of  evaporation  involved : 

,  1.    The  Wimmer  Process.— The  milk 

is  boiled  in  a  vacuum  pan  similar  to  that 
used  in  the  manufacture  of  condensed 
milk.  The  vacuum  pan  has  a  deep  steam 
jacket  for  heating,  but  in  the  place  of  the 
usual  coils,  the  pan  is  equipped  with  a 
mechanical  stirrer.  The  milk  is  con- 
densed at  a  relatively  low  temperature 
and  the  stin-er  revolves  until  the  water 
content  of  the  milk  is  reduced  to  about 
30  per  cent,  and  the  milk  has  become 
porous  and  crumbly,  though  it  still  forms 
a  compact  mass.  The  drying  is  then  com- 
pleted in  the  open  air  and  without  addi- 
tional  heating.      The    product    is    then 

'  ground  to  a  powder.    This  is  the  process 

invented  by  Ole  Bull  Wimmer  of  Copen- 

Fig.   54.     The  Wimmer  milk  -'  ^ 

powder  machine  hngcu,  Denmark. 


184  Condensed  Milk  and  Milk  Powder 

2.  The  Just-Hatmaker  Process. — The  milk  sprays  in  a  thin 
film  over  two  steam  heated  cylinders  or  drums,  about  sixty  inches 
long  and  twenty-four  inches  in  diameter.  The  cylinders  are  about 
one-eighth  of  one  inch  apart  and  revolve  in  opposite  directions.  The 
milk  reaches  the  drums  from  a  supply  tank  located  in  the  center 
above  the  drums.  In  order  to  insure  a  continuous  and  uniform  sup- 
ply of  milk,  a  constant  level  of  about  four  inches  of  milk  is  main- 
tained in  the  supply  tank.  This  process  was  invented  by  J.  R.  Hat- 
maker  of  London,  and  was  patented  in  1902.     Its  objectionable  fea- 


Fig.  55.     The  Just-Hatmaker  milk  drier 

ture  lies  in  the  fact  that  the  excessive  heat  at  which  the  milk  is 
evaporated  impairs  the  solubility  of  the  product.  The  cylinders  are 
charged  with  two  to  three  atmospheres  of  steam  pressure,  causing 
the  heating  surface  to  have  a  temperature  of  about  250  to  280  de- 
grees F. 

3.  The  Eckenburg  and  Passburg  Processes. — In  the  Ecken- 
burg  process  the  milk  is  exposed  in  a  thin  layer  on  the  surface  of  a 
revolving  metal  cylinder  or  drum,  which  is  enclosed  in  a  vacuum 
chamber.  The  cylinder  is  heated  by  passing  hot  water  or  steam 
through  it.  The  fact  that  the  evaporation  takes  place  in  a  vacuum 
chamber  makes  it  possible  to  accomplish  the  drying  at  a  relatively 


Condensed  Miek  and  Milk  Powder 


185 


low  temperature,  although  the  film  of  drying  milk  is  naturally  ex- 
posed for  a  brief  time  to  the  direct  heat  of  the  cylinder.  The 
cylinder  revolves  at  the  rate  of  about  one  revolution  per  minute, 
the  film  of  dried  milk  is  scraped  ofif  the  cylinder  by  a  stationary, 
adjustable  knife  and  the  desiccated  milk  discharged  into  a  receiver. 
The  fresh  milk  enters  the  vacuum  chamber  at  the  bottom  and  the 
revolving  cylinder  is  so  adjusted  that  it  automatically  picks  up  a 
thin  film  of  milk.  This  process  was  invented  by  Dr.  Martin  Ecken- 
burg,  of  Sweden. 


Fig.   56.     The  Eckenburg  milk  drier 


A  similar  apparatus  and  process  was  invented  and  patented  by 
Emil  Passburg  of  IJerlin.  Germany.  This  inventor  recommends 
the  evaporation  of  the  milk  in  the  vacuum  pan  to  about  one-fourth 
its  volume  before  it  enters  the  dryer.  The  dryer  has  a  similar  ar- 
rangement as  that  of  Eckenburg  but  is  equipped  with  an  additional 
device  for  the  purpose  of  insuring  a  film  of  uniform  thickness  of 
the  condensed  milk.  In  some  of  these  dryers  the  milk  is  sprayed 
against  the  drum  and  a  properly  set  knife  regulates  the  thickness  of 
the  film.  The  fact  that  the  milk  is  partly  condensed  before  reaching 
the  drum,  greatly  hastens  the  process  of  drying  and  increases  the 


i86 


Condensed  Milk  and  Milk  Powder 


capacity  of  the  apparatus,  but  it  also  involves  a  more  expensive 
equipment. 

In  this,  as  in  all  other  processes,  where  the  desiccation  is  accom- 
plished by  evaporation  on  a  revolving,  steam-heated  drum,  the  rapid- 
ity and  completeness  of  evaporation  are  regulated  by  the  tempera- 
ture and  speed  of  the  drum. 


I'ig.  57.     The  Passburg  milk  drier 

Courtesy  of  the  Buffalo  Foundry  &  Machine   Co. 

4.  The  Campbell  Process.^ — A  current  of  warm  air  passes 
through  the  milk  upward  until  the  milk  has  become  thick.  The 
remainder  of  the  drying  is  accomplished  by  exposure  to  heated  air. 
The  dried  milk  is  then  ground  to  a  powder.  This  is  the  Campbell 
process,  invented  in  19CX)  and  patented  by  J.  H.  Campbell  of  New 
York  in  1902. 


Condensed  Milk  and  Milk  Powder 
3 


187 


Fig.  58.     The  Campbell  milk  drier 


I  A  concentrating  vessel,  a  outlet,  b  valve,  c  hot  water  jacket,  c^  hot 
water  pipe,  c=  discharge  of  jacket,  B  air  pipe,  e  connecting  hose,  f  stand 
pipe,  g  air-distributing  disc,  t  air  chamber.^II  E  pug  mill,  i  cylinder,  j  hop- 
per, k  chute,  1  horizontal  shaft,  m  blades  for  stirring,  m'  projections  for 
scraping  blades,  F  Vermicelli-machine,  n  hopper,  0  cylindrical  chamber, 
p  piston,  q  spiral  screw,  q'  worm-wheel,  o'  small  holes,  r  endless  traveling 
apron,  s  tray  with  perforated  bottom. — III  G  drier,  t  body  of  drier,  H 
blower,  t'  flue,  u  opening  to  insert  trays,  u'  opening  for  removing  trays, 
vv  endless  chains  with  projections  for  supporting  trays,  w  coil  heater, 
w'  pipe  circulating  hot  water. 


5.  The  Merrell-Gere  Process. — The  milk  is  condensed  in  the 
vacuum  pan  to  about  one  third  to  one  fourth  its  volume.  The  con- 
densed but  still  fluid  milk  is  forced  under  pressure  through  a  fine 
jet,  causing  it  to  be  atomized  and  sprayed  into  a  current  of  hot  air, 
in  an  evaporating  chamber.  This  atomized  liquid  forming  a  mist, 
offers  the  maximum  surface  for  evaporation  of  its  water.  The  hot 
air  absorbs  the  moisture  of  the  milk  almost  instantly  and  the  milk 
drops  to  the  bottom  of  the  chamber  in  the  form  of  a  snow-like  pow- 
der. No  grinding  is  necessary.  This  process  was  invented  by  L.  C. 
and  I.  S.  Merrell  and  W.  B.  Gere,  assignors  to  Merrell-Soule  Co., 
of  Syracuse,  N.  Y.,  and  patented  July  23,  1907.  The  following  are 
the  claims  of  the  patentees: 


[88  Condensed  Milk  and  Milk  Powder 


The   3Ierrell-Ciere   milk  drier 


1  intake  of  milk,  2  vacuum  pan,  3  jacket,  4  steam  intake  into  jacket, 
5  dome  of  pan,  6  vacuum  pumps,  7  condenser,  10  water  column,  11  over- 
flow cistern  for  dry  vacuum  system,  12  discharge  pipe  of  pan,  13  pump, 
14  pressure  gauge,  15  thermometer,  16  sight-glass,  17  regulating  valve, 
18  two-way  draw-off  cock  for  sampling,  19  reservoir,  21  desiccating  cham- 
ber, 22  spray  jet,  23  force  pump,  24  air  pump,  25  compressed  air,  26  air 
drying  chamber,  27  air  heater,  28  stand-pipe,  29  drip  valve,  30  depository 
of  part  of  powder,  31  outlet  of  powder,  32  rotary  gate,  33  receptacle,  34 
rotary  dust  collector  consisting  of  tubular  screen  partitions,  35  openings 
connecting  with  desiccating  chamber,  36  head  closing  tubular  screen,  37 
springs,  38  gear  for  rotating  dust  collector,  39  receptacle,  40  screw  con- 
veyor removing  powder  into  41  which  is  a  chute,  42  automatic  discharge 
valve,  43  beater  to  remove  adhering  powder,  44  spring  of  beater,  45  rod, 
46  toothed  rack,  47  driving  shaft,  48  suction  pump  to  facilitate  removal  of 


Condensed  Milk  and  Milk  Powder  189 

powder,  49  conduit,  50'  casing  inclosing  dust  collector,  51  discharge  of 
casing,  52,  53  and  54  terminal  branches,  55  rotary  valve,  36  auxiliary 
valved  conduit,  57  supplementary  valvecl  conduit,  58,  59,  61,  62,  63  and  64 
equipment  for  treating  either  colloids  or  crystalloids  separately. 

"Claims: 

1.  "The  process  of  obtaining  the  soHd  constituents  of  hquids 
and  semi-hquids,  in  the  form  of  powder,  which  process  consists  in 
concentrating  the  substance  by  removing  a  large  percentage  of  the 
water  therefrom,  converting  the  concentrated  mass  into  a  fine  spray, 
bringing  such  spray  into  a  current  of  dry  air  or  gas  having  an 
avidity  for  moisture  so  that  substantially  all  the  remaining  liquid 
constituents  are  separated  thereby,  conveying  the  dry  powder  into 
a  suitable  collecting  space  away  from  the  air  or  gas  current,  and 
discharging  the  air  or  gas  separately  from  the  dry  powder. 

2.  "The  process  of  obtaining  the  solid  constituents  of  liquids 
and  semi-liquids,  in  the  form  of  powder,  which  process  consists  in 
concentrating  the  substance  by  removing  a  large  percentage  of 
water  therefrom,  converting  the  concentrated  mass  into  a  spray, 
bringing  such  spray  into  a  current  of  dry  heated  air  or  gas  having 
an  avidity  for  the  moisture  of  the  substance  treated,  retaining  the 
atoms  momentarily  in  said  current  so  that  substantially  all  the  re- 
maining moisture  is  converted  into  vapor  and  the  product  is  pre- 
vented by  the  cooling  effect  of  such  evaporation  from  undergoing 
chemical  change,  conveying  the  dry  powder  into  a  suitable  collect- 
ing space  away  from  the  vaporizing  current,  and  discharging  the 
air  or  gas  separately  from  the  dry  powder. 

'In  witness  whereof  we  have  hereunto  set  our  hands  this  7th 
day  of  August,  1906." 

Lewis  C.  Merrell. 
Witnesses:  Irving   S.   Merrell. 

H.  E.  Chase,  William  B.  Gere. 

Howard  P.  Denison." 


iQO  Condensed  Milk  and  Milk  Powder 

The  product  of  the  Merrell  and  Gere  process  is  without  ques- 
tion superior  to  any  milk  powder. manufactured  by  the  various  pro- 
cesses herein  mentioned.  It  embodies  the  three  all  important  char- 
acteristics of  a  desirable  and  successful  milk  powder;  namely,  it 
contains  less  than  the  minimum  amount  of  moisture  which  permits 
of  bacterial  action,  its  butterfat  is  retained  in  the  globular  form  and 
does  therefore  mix  with  water  readily,  forming  a  complete  emul- 
sion, and  its  albumen  is  present  in  its  natural,  non-coagulated  and 
soluble  form,  insuring  complete  solubility  of  this  dried  milk  in 
water. 

In  the  above  classification  of  processes,  only  those  processes 
have  been  discussed  which  produce  true  milk  powders  without  the 
admixture  of  alkalies  or  sugar  and  which  are  commercially  prac- 
tical. Numerous  other  processes  have  been  patented,  especially  in 
European  countries.  Most  of  these  require  the  addition  to  the  milk 
of  either  alkalies,  or  sugar,  or  both,  or  else  their  commercial  applica- 
tion has  not  been  found  commercially  successful. 


Condensed  Milk  and  Milk  Powder 
CHAPTER  XXVII 


191 


PACKING  FOR  THE  MARKET 

The  dried  milk,  reduced  to  a  fine  powder,  is  put  on  the  market 
in  packages  of  various  types  and  sizes.  Small  packages  are  usually 
put  up  in  tin  or  fibre  cans  holding  from  eight  ounces  to  ten  pounds 
of  milk  powder.  These  cans  are  closed  with  a  friction  cap.  The 
bulk  of  dried  milk  is  put  up  in  barrels  which  are  lined  with  parch- 
ment paper  similar  to  the  lining  of  sugar  barrels.  Milk  powder 
should  be  stored  in  a  dry  atmosphere.  When  exposed  to  dampness 
it  is  prone  to  absorb  moisture.  In  this  condition  its  life  is  short- 
ened, as  it  becomes  mouldy  and  spoils. 

COMPOSITION  OF  MILK  POWDER 

Milk  powder  is  made  from  whole  milk,  partly  skimmed  milk 
and  skim  milk.  The  following  figures  show  the  composition  of 
milk  powders  manufactured  by  the  several  diflr'erent  processes. 

Composition  of  Milk  Powders  Manufactured  by  Different 
Processes 


Process 

I'at       Proteids 
per            per 
cent.          cent. 

Lactose 
per 
cent. 

Sucrose 
per 
cent. 

Ash 
per 
cent. 

Water 
per 
cent. 

Whole  milk 

^Merrell  and  Gere 
-J.  R.  Hatmaker 
•'E.  Passburg 

29.20 
21  .70 
22.56 

26.92 
28.70 
20.83 

36.48' 

35-10 
20.87 

28.77 

6.00 
6.50 

5-90 

1.40 
8.00 
4.04 

Half   skimmed 

^Merrell  and  Gere 
"T.    R.    Hatmaker 
^Process  not  known 

15.10 
13.00 
15.  80' 

33-30 
30.57 

37-45 

39-70 
48.85 
33-11 

6.90 
7.28 

7-34 

5-00 

8.30 
6.30 

Skimmed 

'Merrell   and   Gere 
^J.  R.  Hatmaker 

1. 00 
1.02 

37.00 
37.28 

47-00 
46.30' 

8.00 
8.00 

7.00 
7.40 

1  Larsen  and  White,  Milk  Technology 

2  C.  Huyge,  La  poiidre  du  lait.  Revue  generale  du  lait,  VoL  3,  No.  U,  19(M 

s  J.  Mayrhofer,  Leber  einige  Erzeugnisse  der  Milch,  Zeitschr.  f.  d.  Vol.  vii,  No.  11,  1904 
Landw.  Versuchswesen  in  Oesterreich 


192  Condensed  Milk  and  Milk  Powder 

DEFECTS  OF  MILK  POWDERS 

High  Water  Content. — In  order  to  insure  keeping  quality,  milk 
powders  must  be  as  free  from  moisture  as  possible.  Milk  powders 
are  not  sterile,  nor  are  they  supposed  to  contain  preservatives  such 
as  sucrose  and  chemicals.  Their  only  safeguard  against  bacterial 
fermentation  and  spoiling  is  their  comparative  freedom  from  water. 
Unless  the  process  fulfills  this  requirement,  milk  powders  will  not 
keep  and  their  chief  virtue,  which  renders  them  most  valuable,  is 
forfeited. 

Insoluble  Milk  Powders. — If  milk  powders  are  to  take  the  place 
of  fresh  milk  or  condensed  milk  on  the  table  of  the  consumer,  they 
must  be  readily  soluble.  One  of  the  greatest  obstacles  in  the  pro- 
gress of  the  milk  powder  industry,  jias  been  that  the  dried  milk  of 
most  of  the  processes  failed  to  be  readily  and  completely  soluble. 
Earlier  processes  prescribed  the  admixture  to  the  milk  of  alkalies 
in  order  to  preserve  the  solubility  of  the  proteids,  which  otherwise 
were  rendered  insqluble  by  the  high  heat  of  the  respective  pro- 
cesses. It  is  obvious  that  a  dried  milk,  the  solubility  of  which  can 
be  retained  only  by  the  admixture  of  alkalies,  is  a  poor  substitute 
for  milk,  and  the  very  principle  of  adding  chemicals  to  a  food  prod- 
uct like  milk,  is  contrary  to  our  ideal  of  honest  and  successful  man- 
ufacture of  high  quality  of  product.  In  the  most  approved  pro- 
cesses now  in  use,  the  milk  is  never  exposed  to  temperatures  high 
enough  to  render  the  proteids  of  the  resulting  milk  powder  insol- 
uble, and  in  their  applications  the  use  of  solvents  is  unnecessary. 

Non-miscible  Milk  Powders. — The  miscibility  of  the  dried  milk 
with  water  depends,  aside  from  its  solubility,  on  the  physical  con- 
dition of  its  butter  fat  and  the  casein.  If  the  process  employed  is 
such  as  to  destroy  the  globular  form  of  the  fat  globules,  it  is  im- 
possible to  reduce  the  dried  milk  to  a  homogeneous  fluid,  similar 
to  normal  fresh  milk.  The  fat  in  such  milk  will  rise  to  the  surface 
quickly,  similar  to  the  fat  in  a  mixture  of  oil  and  water. 

In  fresh  and  normal  milk  the  casein  is  present,  not  in  solution, 
but  in  suspension.  The  particles  of  casein  are  very  minute  and 
form  an  intimate  mechanical  union  with  the  water.  In  this  condi- 
tion they  are  present  in  the  form  of  a  homogeneous  emulsion  with 
the  other  ingredients  of  the  milk.  •   When  the  milk  is  desiccated  at 


Condensed  Milk  and  Milk  Powder  193 

high  temperatures,  the  particles  of  casein  lose  their  property  of 
emulsifying  and  when  the  desiccated  milk  is  redissolved,  the  casein 
fails  to  be  miscible.  dropping  to  the  bottom  in  the  form  of  finely 
divided,  insoluble  curd.  In  order  to  produce  milk  powder  which 
is  miscible  in  water,  the  process  and  heat  used  must  be  such,  as  to 
permit  the  casein  to  pass  into  the  finished  product  in  its  natural 
state. 

Both  of  these  requirements  of  miscible  milk  powder,  the 
globular  state  of  the  fat  globules  and  the  natural  emulsifying  prop- 
erties of  the  casein,  seem  to  be  adequately  met  and  complied  with 
in  the  product  of  the  ]\Ierrcll  and  Gere  process. 

Rancid  Milk  Powder.— From  the  biological  point  of  view,  milk 

powder,  properly  made  and  with  a  minimum  moisture  content, 
cannot  decompose.  Unfortunately,  one  of  the  constituents  of  dried 
milk,  the  butterfat,  is  prone  to  undergo  chemical  changes  upon 
exposure  to  light,  heat  and  air.  The  less  stable  fatty  acids,  espe- 
cially the  oleic  acid,  the  glyceride  of  which  is  an  unsaturated  fat, 
oxidize  readily,  giving  the  product  a  rancid  or  tallowy  flavor. 
Even  the  most  experienced  manufacturers  of  milk  powder,  using 
the  most  perfected  processes  now  known,  admit  that  milk  powder 
made  from  whole  milk,  or  partly  skimmed  milk,  will  become  rancid 
when  exposed  to  air,  light  and  ordinary  temperatures. 

Experience  has  amply  demonstrated  that  whole  milk  powder 
will  deteriorate  and  become  rancid  very  much  under  the  same  con- 
ditions as  butter.  In  order  to  prevent  whole  milk  powder  from 
becoming  rancid,  it  must  be  stored  in  the  cold. 

MARKETS 

Owing  to  its  relatively  poor  keeping  (jualit}',  the  markets  for 
whole  milk  powder  are  limited.  It  is  a  most  ideal  substitute  for 
fresh  milk  or  condensed  milk,  if  used  when  fresh  or  whenever,  in 
its  storage  and  transportation,  it  can  be  protected  by  cold.  This 
requirement,  however,  is  a  serious  obstacle  to  its  omniusefulness 
and  will  remain  a  hinderance  to  its  introduction  in  the  pantry  of 
the  consuiucr,  until  the  manufacturer  succeeds  in  correcting  this 
defect. 

Skim  milk  powder,  on  the  other  hand,  is  free  from  this  draw- 
back, and  when  properly  made  and  kept  dry,  it  keeps  indefinitely. 


194  Condensed  Milk  and  Milk  Powder 

It  has  become  a  most  valuable  dairy  product  and  its  uses  are  mani- 
fold. It  is  used  in  the  consumer's  kitchen,  in  bakeries  and  con- 
fectioners' establishments,  in  the  manufacture  of  ice  cream,  fer- 
mented milk  beverages,  and  starters  for  cream  ripening  where  milk 
and  skim  milk  are  not  available;  in  the  preparation  of  baking 
powder,  of  pure  lactic  acid  cultures  for  creameries  and  cheese 
factories,  of  drugs,  choice  toilet  soaps,  etc.  In  European  countries, 
the  chocolate  factories  purchase  vast  quantities  of  skim  milk  pow- 
der in  the  manufacture  of  milk  chocolate  and  allied  products,  and 
manufacturers  of  diverse  prepared  food  products  such  as  cereals, 
soups,  noodles,  and  vegetables,  furnish  additional  markets  for  this 
new  dairy  product. 


CHAPTER  XXVIII 
DRIED  BUTTERMILK  AND  DRIED  WHEY 

These  by-products  of  the  creamery  and  cheese  factory  can  be 
reduced  to  a  powder  in  a  similar  way  and  by  the  same  processes 
and  machinery,  as  are  used  in  the  manufacture  of  dried  milk  and 
dried  skim  milk. 

Dried  buttermilk  makes  a  splendid  chicken  feed,  both  for  egg 
production  and  for  fattening  chickens.  It  is  best  diluted  to  about 
the  original  buttermilk  (one  part  powder  in  ten  parts  water)  and 
mixed  with  the  grain  feed  into  a  mush.  Like  fresh  buttermilk,  so 
is  dried  buttermilk  a  wholesome,  nutritious  and  easily  digested  food 
and  recommends  itself  especially  to  persons  with  weak  digestion. 
When  properly  made,  buttermilk  powder  keeps  indefinitely  and  may, 
therefore,  be  available  for  immediate  use  at  all  times. 

The  following  analyses  show  the  composition  of  buttermilk 
powder  and  of  the  fresh  buttermilk  from  which  it  was  made. 


Condensed  MiIvK  and  Milk  Powder 
composition  of  buttermilk  powder 


195 


Butter   fat 

Proteids 

Lactose 

Ash 

Acidity 

Iron  (Fe.Og) 

Water 

Total 


Fresh  buttermilk 

1 .  17  per  cent. 
3.00  per  cent. 

2 .  97  per  cent. 
.  85  per  cent. 
.60  percent. 
.  GO  per  cent. 

9 1 .  63  per  cent. 


Buttermilk    powder 
1 1 .  70  per  cent. 
36.24  percent. 
35 .  50  per  cent. 

8.25  per  cent. 

6.00  per  cent. 

1.92  per  cent. 

4.32  per  cent. 


100.22  per  cent. 


103.93  per  cent. 


^  The  buttermilk  of  which  the  composition  is  shown  in  the  above 
table  was  made  at  the  plant  of  the  Buffalo  Foundry  and  Machine 
Company,  Buffalo,  N.  Y.,  under  the  supervision  of  the  writer.  The 
machine  used  was  of  the  Passburg  type.  The  buttermilk  was  fur- 
nished by  Schlosser  Bros.,  of  Frankfort,  Indiana.  This  batch  of 
buttermilk  happened  to  be  abnormally  high  in  butterf at ;  therefore 
the  large  butterfat  content  of  the  finished  product.  The  iron  found 
in  the  dried  buttermilk  is  probably  due  to  the  fact  that  the  drying 
drum  of  the  desiccator  was  of  iron  and  was  acted  upon  by  the 
high  per  cent,  of  lactic  acid.  About  thirty  pounds  of  steam  pressure 
were  used  in  the  drying  drum,  the  temperature  in  the  vacuum 
chamber  was  125  degrees  F.  and  the  vacuum  twenty-five  to  twenty- 
six  inches  of  the  mercury  column. 

This  buttermilk  powder  had  a  nice,  clean,  acid  taste,  it  was 
much  relished  by  all  who  sampled  it  and,  when  fed  to  chickens  for 
fattening,  produced  satisfactory  gains  in  weight. 

Whey  powder  is  manufactured  in  a  similar  manner.  Its  chief 
value  lies  in  its  usefulness  in  the  diet  of  infants  and  invalids,  with 
whom  the  consumption  of  casein  produces  digestive  disturbances. 
Since  fresh  whey  is  often  not  obtainable,  the  whey  powder,  the  good 
keeping  quality  of  which  permits  of  keeping  it  on  hand,  furnishes 
an  admirable  substitute. 

The  chief  objection  to  these  desiccated  dairy  by-products,  such 
as  dried  skim  milk,  dried  buttermilk,  and  dried  whey,  is  that  the 
cost  of  reducing  them  to  dryness  is   somewhat  out  of  proportion 


Hiinziker,  Indiana  Agricultural  Experiment  Station,  Twenty-sixth  Annual  Report,  1913 


ig6  Condensed  Milk  and  Milk  Powder 

with  their  actual  value,  as  compared  with  the  raw  or  condensed 
product.  Dried  skim  milk,  for  instance,  sells  at  thirteen  to  fourteen 
cents  per  pound.  Wheii  diluted  to  the  consistency  of  the  raw  skim 
milk,  one  -pound  of  powder  yields  about  ten  or  eleven  pounds  of 
skim  milk,  costing  between  $1.25  to  $1.40  per  hundred  pounds, 
which  is  almost  the  price  of  fresh  whole  milk.  It  is  obvious,  that 
the  average  creamery  cannot  afiford  to  make  starter  at  the  rate  of 
$1.25  to  $1.40  per  hundred  pounds. 

For  the  same  reason  the  demand  for  dried  buttermilk  and  dried 
whey  is  as  yet  very  limited.  These  products,  in  their  natural  state, 
contain  too  small  a  proportion  of  the  valuable  ingredients,  and  they 
are  too  cheap  to  justify  the  high  cost  of  manufacture,  in  order  to 
place  them  on  the  market  in  the  dry  form.  This,  of  course,  does 
not  apply  to  the  use  of  dried  skim  milk  for  the  many  industrial  pur- 
poses mentioned,  where  properties,  other  than  the  mere  food  value, 
determine  the  real  merits,  value  and  usefulness  of  the  product. 


Condensed  Milk  and  Milk  Powder  197 


PART    VIII 

TESTS  AND  ANALYSES  OF  MILK,  CONDENSED 
MILK  AND  MILK  POWDER 

CHAPTER  XXIX 

PRACTICAL  METHODS    OF    SYSTEMATIC  EXAMINATION 
OF  PRODUCT  FOR  MARKETABLE  PROPERTIES 

The  manufacturer  should  know  at  all  times  the  quality  and 
keeping  quality  of  his  product.  He  should  have  a  systematic  check, 
not  only  on  his  product  stored  in  the  factory,  but  also  on  the  goods 
in  transit  and  on  the  market,  in  order  to  promptly  detect  goods  that 
show  signs  of  deterioration.  This  will  enable  him  to  investigate  the 
cause  of  the  defect,  to  prevent  its  recurrence  and  to  avoid  spoiled 
goods  from  reaching  the  consumer.  The  following  simple  method 
of  systematic  examination  has  been  found  effective  in  keeping  a 
reliable  check  on  each  batch  until  the  product  is  old  enough  to  have 
proved  its  immunity  from  the  usual  specific  defects. 

Number  of  Samples  Needed. — Five  cans  of  every  batch  of 
condensed  milk  or  evaporated  milk,  bearing  the  corresponding  batch 
number,  are  reserved  for  this  purpose.  For  convenience's  sake  these- 
sample  cans  are  best  stored  on  shelves  about  fifteen  inches  wide  and 
five  inches  apart.  These  dimensions  are  sufficient  to  conveniently 
accommodate  five  i6-ounce  cans  of  one  and  the  same  batch  and 
placed  in  a  row,  one  behind  the  other.  These  shelves  should  be  in- 
stalled in  a  place,  preferably  the  office,  where  the  cans  may  be  ex- 
posed to  similar  changes  and  extremes  of  temperature,  as  is  the  case 
in  transit  and  in  the  retail  store.  The  cans  of  sweetened  condensed 
milk  should  be  placed  on  these  shelves  bottom-side  up.  The  cans 
of  evaporated  milk  should  be  placed  on  the  shelves  right-side  up. 


198  Condensed  Milk  and  Miek  Powder 

Frequency  of  Examination.^ — Every  day  one  can  of  condensed 
milk  or  other  product,  one,  three,  ten,  thirty  and  sixty  days  old,  re- 
spectively, is  opened  and  the  contents  are  carefully  examined  for 
thickness,  smoothness,  sugar  sediment,  curdiness,  fat  separation, 
color,  flavor,  fermentation-changes,  etc. 

Technique  of  Examination. — Since  the  temperature  of  the 
product  influences  its  apparent  thickness,  it  is  desirable  to  examine 
the  condensed  milk  at  a  uniform  temperature,  preferably  60  or  70 
degrees  F.  This  is  best  accomplished  by  the  use  of  a  water-tight 
tray  of  galvanized  iron  or  tin,  about  twelve  inches  long,  nine  inches 
wide,  and  three  and  a  half  inches  deep,  with  an  overflow  about  two 
and  a  half  inches  above  the  bottom.  Every  day,  at  a  regular  hour, 
the  samples  of  the  ages  above  stated,  are  placed  into  this  tray,  con- 
taining water  at  the  desired  temperature  (60  to  70  degrees  F.),  about 
thirty  minutes  before  the  cans  are  opened.  All  cans  should  be 
placed  in  the  tray  right-side  up. 

Upon  opening  the  cans,  the  coating  on  the  lid  shows  the  pres- 
ence of  sugar  sediment  and  of  lumps  of  curd  in  the  case  of  sweet- 
ened condensed  milk,  and  a  layer  of  thick  and  buttery  cream  in  the 
case  of  evaporated  milk.  A  perfectly  clear  lid,  without  any  coating, 
indicates  the  freedom  of  the  product  from  these  defects.  In  the 
case  of  fermented  milk  the  ends  of  the  cans  are  usually  bulged. 
Upon  opening,  a  part  of  the  contents  is  forced  out.  The  thickness 
is  estimated  by  inserting  a  spatula,  or  spoon,  or  by  pouring,  and  the 
flavor  and  smoothness  are  determined  by  tasting. 

The  observations  should  be  carefully  recorded  in  a  book  re- 
served for  this  purpose,  and  any  changes  observed,  as  the  milk  ad- 
vances in  age,  should  be  noted. 

Interpretation  of  Results. — Most  of  the  physical  and  mechan- 
ical defects  appear  in  milk  from  one  to  ten  days  old.  Defects  re- 
sulting from  fermentation  processes  generally  become  noticeable 
two  to  three  weeks  after  manufacture. 

Fluctuations  in  the  thickness,  from  batch  to  batch,  indicate  lack 
of  proper  attention  on  the  part  of  the  pan-man  to  the  "striking"  of 
the  batches.  Sugar  sediment  shows  the  need  of  closer  attention  to 
the  solution  of  sucrose  and  the  cooling  of  the  condensed  milk. 
Lumps   and   buttons   suggest   the  acceptance  of   a  poor  quality  of 


Condensed  Milk  and  Milk  Powder  199 

fresh  milk,  or  unsanitary  condition  of  milk  cans,  vats,  pipes  and 
conveyors  in  the  factory,  or  unclean  tin  cans.  Fat  separation  and 
curdiness  of  evaporated  milk  suggest  a  faulty  process.  Fermenta- 
tion of  sweetened  condensed  milk  urges  investigation  of  the  quality 
and  condition  of  the  sugar  and  of  the  sanitary  condition  of  all 
apparatus  and  conveyors  of  milk,  condensed  milk  and  sugar,  from 
the  forewarmers  to  the  sealing  machine.  Fermented  evaporated 
milk  points  to  incomplete  sterilization  or  leaky  tin  cans,  etc. 

Systematic  Examination  a  Necessary  Feature  of  Economic 
Manufacture. — Manufacturers  who  neglect  to  conduct  a  systematic 
examination  of  their  product,  similar  to  that  outlined  above,  fre- 
quently argue  that  they  cannot  afford  to  waste  five  cans  out  of 
every  batch. 

This  is  indeed  a  mistaken  conception  of  economy.  With  the 
exception  of  fermented  milk,  the  "cut-opens"  can  be  emptied  into 
the  succeeding  batch,  so  that  all  that  is  lost  is  the  tin  cans.  Fer- 
mented goods  cannot  be  utilized  anyway,  neither  on  the  market,  nor 
elsewhere.  Their  loss,  therefore,  will  occur  whether  in  the  form 
of  "cut-opens,"  or  cans  intended  for  the  trade. 

The  slight  waste  incurred  by  cutting  open  cans  with  sound 
contents  is  insignificant  as  compared  with  the  incalculable  savings 
which  this  practice  may  make  possible,  by  the  early  detection  of 
faulty  goods  and  the  prevention  of  their  recurrence,  by  enabling 
the  manufacturer  to  withdraw  suspicious  goods  from  the  market 
before  they  have  ruined  the  reputation  of  the  respective  brands,  and 
by  furnishing  a  reliable  check  on  the  work  of  the  employees,  whose 
knowledge,  that  their  product  is  subjected  to,  and  must  pass  a  rigid 
e.xamination,  acts  as  a  moral  stimulus  for  high  quality,  skill  and 
carefulness. 


Condensed  Milk  and  Milk  Powder 


CHAPTER  XXX 

CHEMICAL  TESTS  AND  ANALYSES  OF  MILK,  SWEETENED 

CONDENSED  MILK,  EVAPORATED  MILK  AND 

MILK  POWDERS 

In  assembling  these  methods  of  analysis,  preference  has  been 
given  the  "Official  and  Provisional  Methods  of  Analysis/'  published 
by  the  American  Association  of  Agricultural  Chemists.^  The  of- 
ficial methods  have  been  modified  and  supplemented  by  other 
methods  in  numerous  cases,  wherever,  in  the  judgment  of  the  writer 
and  others,  such  modifications  and  substitutions  are  better  adapted 
for  analysis  of  these  special  products.  A  special  effort  has  further 
been  rnade  to  include  in  this  chapter  modifications  and  abbreviations 
of  tests  and  analyses,  adapted  for  the  use  of  the  factory  operator, 
whose  knowledge,  skill,  facilities  and  time  are  too  limited  to  enable 
him  to  successfully  follow  the  directions  of  the  official  methods,  or  to. 
execute  delicate  and  difficult  chemical  analyses. 

For  practical  factory  tests  of  fresh  milk  on  the  receiving  plat- 
form, determining  its  fitness  for  condensing,  the  reader  is  referred 
to  Chapter  III,  "Factory  Tests  for  Purity,"  pp.  29  to  34. 

MILK 

SPECIFIC  GRAVITY 

Aerometric  Method,  by  Me.vns  of  the  Quevenne  Lactom- 
eter.— Use  an  accurate  Quevenne  lactometer  with  thermometer 
attachment,  and  a  lactometer  cylinder  about  ten  inches  high  and 
one  and  a  half  inches  wide.  Fill  the  cylinder  with  milk  at  a  tem- 
perature between  55  and  65  degrees  F.  Insert  the  lactometer  and 
when  it  has  found  its  equilibrium,  note  the  point  on  the  scale  at  the 
surface  of  the  milk.  The  correct  temperature  is  60  degrees  F.  For 
every  degree  Fahrenheit  above  60  add  one  tenth  point  to  the  ob- 
served reading,  and  for  every  degree  Fahrenheit  below  60  deduct 
one  tenth  point  from  the  observed  reading.     This  rule  holds  good 


United  States  Department  of  Agriculture,  Bureau  of  Chemistry.  Bulletin  No.  107,  1912 


Condensed  Milk  and  Milk  Powder  201 

only,   when  the   range  of  temperature  is   within  the  hmits  of   55 
degrees  and  65  degrees  F. 

The  specific  gravity  is  calculated  by  adding  1000  to  the  lactom- 
eter reading  and  dividing  the  sum  by  1000.  Example:  Lactometer 
reading    is    31    at    65    degrees    F.      Corrected    reading    is    31.5; 

.   31-5  +  1000 
specific  gravity  is =:  1.03 15. 

Gravimetric  Determination. — This  consists  of  the  filling  of 
a  perfectly  dry  picnometer  or  other  graduated  flask  of  known 
measure,  with  milk  at  the  standard  temperature  (60  degrees  F.,  or 
15.5  degrees  C. )  and  weighing  the  flask  and  contents.  The  weight 
of  the  flask  is  then  deducted  from  the  weight  of  the  flask  plus  con- 
tents and  the  difference  is  divided  by  the  weight  of  an  equal  volume 
of  water  at  standard  temperature.  The  result  is  the  specific  gravity 
of  the  milk. 

The  Westphal  balance  method  furnishes  another  accurate 
means  of  determining  the  specific  gravity.  Both,  the  gravimetric 
method  and  the  Westphal  balance  method,  while  accurate  when 
operated  by  the  skillful  chemist,  require  considerable  time.  Ex- 
perimental comparisons  have  demonstrated  that,  for  all  practical 
purposes,  the  Quevenne  hydrometer,  when  accurately  graduated, 
yields  correct  results,  and  the  simplicity  and  rapidity  of  its  operation 
render  its  use  in  the  determination  of  the  specific  gravity  of  milk 
highly  advantageous  and  satisfactory. 

TOTAL  SOLIDS 

By  Means  oe  the  Babcock  Formula. — For  rapid  and  reason- 
ably accurate  work  the  total  solids  of  milk  are  best  determined  by 
the  use  of  the  Babcock  formula,  which  is  as  follows: 

L 

Total  solids  =  +  1.2  x  f. 

4 

L  =  Quevenne  lactometer  reading. 

f  =  per  cent,  of  fat. 

Example :    Lactometer  reading  is  32 ;  per  cent,  fat  is  4. 

32 

Total  solids  =  +  i  .2  x  4  =  12.8  per  cent. 

4 


202"  Condensed  Milk  and  Milk  Powder 

Gravimetric  Method. — "Heat  from  three  to  five  grams  of 
milk  at  the  temperature  of  boiHng  water  until  it  ceases  to  lose 
weight,  using  a  tared  flat  dish  of  not  less  than  5  c.c.  diameter.  If 
desired,  from  fifteen  to  twenty  grams  of  pure,  dry  sand  may  be 
previously  placed  in  the  dish.  •  Cool  in  a  desiccator  and  weigh  rap- 
idly to  avoid  absorption  of  hygroscopic  moisture." 

ASH 
"Weigh  about  twenty  grams  of  milk  in  a  weighed  dish,  add 
6  c.c.  of  nitric  acid,  evaporate  to  dryness,  and  ignite  at  a  tempera- 
ture just  below  redness  until  the  ash  is  free  from  carbon." 

TOTAL    NITROGEN 
Place  about  five  grams  of  milk  in  a  Kjeldahl  digestion  flask  and 
proceed,  without  evaporation,  as  described  under  "Gunning  Method" 
for  the   determination   of    nitrogen.      Multiply   the   percentage   of 
nitrogen  by  6.38  to  obtain  nitrogen  compounds. 

Gunning  Method 

APPARATUS 

"(a)  Kjeldahl  flasks  for  both  digestion  and  distiUation. — These 
are  flasks  having  a  total  capacity  of  about  550  c.c.  made  of  hard, 
moderately  thick,  and  well-annealed  glass.  When  used  for  distilla- 
tion the  flasks  are  fitted  with  rubber  stoppers  and  bulb  tubes,  as 
given  under  distillation  flasks. 

{h)  Kjeldahl  digestion  flasks. — These  are  pear- shape,  round- 
bottomed  flasks,  made  of  hard,  moderately  thick,  well-annealed  glass, 
having  a  total  capacity  of  about  250  c.c.  They  are  22  cm.  long  and 
have  a  maximum  diameter  of  6  cm.,  tapering  gradually  to  a  long 
neck,  which  is  2  cm.  in  diameter  at  the  narrowest  part  and  flared 
a  little  at  the  edge. 

(c)  Distillation  flasks. — For  distillation  a  flask  of  ordinary 
shape,  of  about  550  c.c.  capacity,  may  be  used.  It  is  fitted  with  a 
rubber  stopper  and  with  a  bulb  tube  above  to  prevent  the  possibility 
of  sodium  hydrate  being  carried  over  mechanically  during  distilla- 
tion. The  bulbs  may  be  about  3  cm.  in  diameter,  the  tubes  being  of 
the  same  diameter  as  the  condenser  and  cut  ofif  obliquely  at  the 
lower  end,  which  is  fastened  to  the  condenser  bv  a  rubber  tube." 


Condensed  Milk  and  Milk  Powder  203 

PREPARATION  OF  REAGENTS 

"(a)  Potassium  sulphate. — ^This  reagent  should  be  pulverized 
before  using. 

■  (b)  Sulphuric  acid. — The  sulphuric  acid  should  have  a  specific 
gravity  of  1.84.  It  should  be  C.  P.  containing  no  nitrates  nor  am- 
monium sulphate. 

{c)     Sulphuric  acid. — .V-io  solution. 

(d)  Standard  alkali  solution. — The  strength  of  this  solution 
relative  to  the  acid  must  be  accurately  determined,  N-io  solution. 

(e)  Metallic  mercury  or  mercuric  oxid. — If  mercuric  oxid  is 
used,  it  should  be  prepared  in  the  wet  way,  but  not  from  mercuric 
nitrate. 

(/)  Granulated  zinc  or  pumice  stone. — One  of  these  reagents 
is  added  to  the  contents  of  the  distillation  flasks,  when  found  nec- 
essary, in  order  to  prevent  bumping. 

(g)  Potassium  sulphid  solution. — A  solution  of  forty  grams 
of  commercial  potassium  sulphid  in  one  liter  of  water. 

(h)  Sodium  hydroxid  solution. — A  saturated  solution  of  so- 
dium hydroxid  free  from  nitrates. 

(/)  Indicator. — A  solution  of  cochineal  is  prepared  by  digest- 
ing and  frequently  agitating  three  grams  of  pulverized  cochineal  in 
a  mixture  of  50  c.c.  of  strong  alcohol  and  200  c.c.  of  distilled  water 
for  a  day  or  two  at  ordinary  temperatures.  The  filtered  solution  is 
employed  as  indicator." 

DETER-MINATIOX 

Place  the  substance  to  be  analyzed  in  a  digestion  flask,  employ- 
ing from  0.7  to  3.5  grams,  according  to  its  proportion  of  nitrogen. 
Add  ten  grams  of  powdered  potassium  sulphate  and  from  15  to  25 
c.c.  (ordinarily  about  20  c.c.)  of  sulphuric  acid.  Conduct  the  di- 
gestion by  starting  with  a  temperature  below  boiling  point  and  in- 
creasing the  heat  gradually  until  frothing  ceases.  Digest  for  a  time 
after  the  mixture  is  colorless  or  nearly  so,  or  until  oxidation  is  com- 
plete. Do  not  add  either  potassium  permanganate  or  potassium 
sulphid.  Dilute,  neutralize,  distil,  and  titrate  with  standard  alkali. 
In  neutralizing,  it  is  convenient  to  add  a  few  drops  of  phenol- 
phthalein  indicator,  by  which  one  can  tell,  when  the  acid  is  complete- 
ly neutralized,   remembering  that  the   pink  color,   which   indicates 


204  Condensed  Milk  and  Milk  Powder 

an  alkaline  reaction,  is  destroyed  by  a  considerable  excess  of  strong 
fixed  alkali. 

CASEIN  AND  ALBUMIN 

"(a)  Casein.— The  determination  should  be  made  when  the 
milk  is  fresh,  or  nearly  so.  When  it  is  not  practicable  to  make  this 
determination  within  twenty-four  hours,  add  one  part  of  formal- 
dehyde to  twenty-five  hundred  parts  of  milk,  and  keep  in  a  cool 
place.  Place  about  ten  grams  of  milk  in  a  beaker  with  about  90  c.c. 
of  water  at  40  degrees  to  42  degrees  C,  and  add  at  once  1.5  c.c.  of 
a  10  per  cent,  acetic  acid  solution.  Stir  with  a  glass  rod  and  let 
stand  from  three  to  five  minutes  longer.  Then  decant  or  filter,  wash 
two  or  three  times  with  cold  water  by  decantation,  and  transfer  pre- 
cipitate completely  to  filter.  Wash  once  or  twice  on  filter.  The 
filtrate  should  be  clear,  or  nearly  so.  If  it  be  not  clear  when  it  first 
runs  through,  it  can  generally  be  made  so  by  two  or  three  repeated 
filtrations,  after  which  the  washing  of  the  precipitate  can  be  com- 
pleted. Determine  nitrogen  in  the  washed  precipitate  and  filter  by 
the  Gunning  method.  To  calculate  the  equivalent  amount  of  casein 
from  the  nitrogen  multiply  by  6.38. 

In  working  with  milk  which  has  been  kept  with  preservatives, 
the  acetic  acid  should  be  added, in  small  proportions,  a  few  drops 
at  a  time,  with  stirring,  and  the  addition  continued  until  the  liquid 
above  the  precipitate  becomes  clear  or  very  nearly  so. 

(b)  Albumin. — Exactly  neutralize  with  caustic  alkali  the  fil- 
trate obtained  in  the  preceding  operation  (a),  add  0.3  c.c.  of  a  10 
per  cent,  solution  of  acetic  acid  and  heat  the  liquid  to  the  tempera- 
ture of  boiling  water  until  the  albumin  is  completely  precipitated, 
collect  the  precipitate  on  a  filter,  wash,  and  determine  the  nitrogen 
therein.     Nitrogen  multiplied  by  6.38  equals  albumin." 

In  the  place  of  the  above  method  the  per  cent,  of  albumin  may 
be  determined  by  subtracting  the  per  cent,  of  casein  from  the  per 
cent,  of  total  nitrogen. 

MILK  SUGAR      (LACTOSE) 

Optical  Method 

PREPARATION  OF  REAGENTS 

"(a)  Acid  mercuric  nitrate. — Dissolve  mercury  in  double  its 
weight  of  nitric  acid,  specific  gravity  1.42,  and  dilute  with  an  equal 


Condensed  Milk  and  Milk  Powder 


205 


volume  of  water.  One  cubic  centimeter  of  this  reagent  is  sufficient 
for  the  quantities  of  milk  mentioned  below.  Larger  quantities  may 
be  used  without  affecting  the  results  of  polarization. 

(b)  Mercuric  iodid  zcith  acetic  acid. — Mix  33.2  grams  of  po- 
tassium iodid,  13.5  grams  of  mercuric  chlorid.  20  c.c.  of  glacial 
acetic  acid,  and  640  c.c.  of  water." 

DETERMIXATION 

The  milk  should  be  at  a  constant  temperature,  and  its  specific 
gravity  determined  with  a  delicate  hydrometer.  When  greater  ac- 
curacy is  required,  a  pycnometer  is  used. 

The  quantities  of  the  milk  measured  for  polarization  vary  with 
the  specific  gravity  of  the  milk  as  well  as  with  the  polariscope  used. 
The  quantity  to  be  measured  in  any  case  will  be  found  in  the  fol- 
lowing table. 

"Determination  of  Volume  of  Milk  Sample 

Volume  of  milk  to  be  used 


Specific 
gravity 

For  polariscopes  of  which  the 

sucrose  normal  weight  is 

16.19  grams 

Cubic  centimeters 

For  polariscopes  of  which  the 

sucrose  normal  weight  is 

26.048  grams 

Cubic  centimeters 

I  .024 

60.0 

64.4 

I  .026 

59-9 

64 

3 

1.028 

59-8 

64 

15 

1.030 

59-7 

64 

0 

1.032 

59-6 

63 

9 

1.034 

59-5 

63 

8 

I -035 

59-35 

63 

7 

Place  the  quantity  of  milk  indicated  in  the  table,  in  a  flask 
graduated  at  102.4  c.c.  for  a  Laurent  or  102.6  c.c.  for  a  Ventzke 
polariscope  (Mohr  c.c).  Add  i  c.c.  of  mercuric  nitrate  solution 
or  30  c.c.  of  mercuric  iodid  solution  (an  excess  of  these  reagents 
does  no  harm),  fill  to  the  mark,  agitate,  filter  through  a  dry  filter, 
and  polarize.  It  is  not  necessary  to  heat  before  polarizing.  In  case 
a  200  mm.  tube  is  used,  divide  the  polariscope  reading  by  3  when 
the  sucrose  normal  weight  for  the  instrument  is  16.19  grams,  or  by 
2  when  the  normal  weight  for  the  instrument  is  26.048.     AXHien  a 


2o6  Condensed  Milk  and  Milk  Powder 

400  mm.  tube  is  used,  these  divisors  become  6  and  4,  respectively. 
For  the  calculation  of  the  above  table  the  specific  rotary  power  of 
lactose  is  taken  as  52.53  degrees,  and  the  corresponding  number  of 
sucrose  as  66.5  degrees.  The  lactose  normal  weight  to  read  100 
degrees  on  the  sugar  scale  for  Laurent  instruments  is  20.496  grams, 
and  for  Ventzke  instruments,  32.975  grams.  In  case  metric  flasks 
are  used  the  weights  here  mentioned  must  be  reduced  to  16.160  and 
26.000  grams,  respectively. " 

Low's  Volumetric  Method,  Modifie:d 

PREPARATION   OF  REAGENTS 

"(a)  Copper  sulphate  solution. — Dissolve  34.639  grams  of 
CUSO4.5H2O  in  water  and  dilute  to  500  c.c. 

{h)  Alkaline  tartrate  solution. — Dissolve  173  grams  of  Ro- 
chelle  salts  and  50  grams  of  sodium  hydroxid  in  water  and  dilute 
to  500  c.c. 

(c)  Mixed  solution. — Mix  equal  volumes  of  solutions  (a)  and 
{b)  immediately  before  use. 

{d)  Standardization  of  the  thiosulphate  solution. — Prepare  a 
solution  of  sodium  thiosulphate,  dissolving  24.659  grams  of  pure 
crystals  to  1000  c.c.  Weigh  6.36  grams  copper  foil.  Dissolve  by 
warming  in  minimum  amount  of  nitric  acid  and  water  required. 
Boil  to  expel  the  red  fumes,  add  160  c.c.  strong  bromine  water  and 
boil  until  the  bromine  is  thoroughly  expelled.  Remove  from  the 
heat  and  add  a  slight  excess  of  strong  ammonium  hydroxid  ;  223  c.c. 
is  about  the  right  amount.  Again  boil  until  the  excess  of  ammonia 
is  expelled,  as  shown  by  a  change  of  color  of  the  liquid,  and  partial 
precipitation.  Now  add  a  slight  excess  of  strong  acetic  acid  ( 100 
to  130  c.c.  of  80  per  cent,  acid)  and  boil  for  a  minute.  Cool  to 
room  temperature  and  dilute  to  1000  c.c.  Titrate  a  known  amount 
(10  to  15  c.c.)  of  the  copper  solution,  to  which  10  c.c.  of  a  25  per 
cent,  solution  of  pure  potassium  iodid  has  been  added,  with  the 
thiosulphate  solution  until  the  brown  tinge  has  become  weak,  then 
add  sufficient  starch  liquor  to  produce  a  marked  blue  coloration. 
Continue  the  titration  cautiously  until  the  color  due  to  free  iodin 
has  entirely  vanished.  The  blue  color  changes  toward  the  end  to 
a  faint  lilac.  If  at  this  point  the  thiosulphate  be  added  drop  by  drop 
and  a  little  time  be  allowed  for  complete  reaction  after  each  addition. 


Condensed  Milk  and  Milk  Powder  207 

there  is  no  difficulty  in  determining  the  end  point  within  a  single 
drop.  One  cubic  centimeter  of  the  thiosulphate  solution  will  be 
found  to  correspond  to  .00636  grams  of  copper." 

DETERMIXATION  OF  COPPER 

"After  washing  the  precipitated  cuprous  oxid,  cover  the  gooch 
with  a  watch  glass  and  dissolve  the  oxid  by  means  of  5  c.c.  of  warm 
nitric  acid  (1:1)  poured  under  the  watch  glass  with  a  pipette.  Catch 
the  filtrate  in  a  flask  of  250  c.c.  capacity,  wash  watch  glass  and 
gooch  free  of  copper ;  50  c.c.  of  water  will  be  sufficient.  Boil  to 
expel  red  fumes,  add  5  c.c.  of  bromin  water,  boil  off  the  bromin, 
and  proceed  exactly  as  in  standardizing  the  thiosulphate." 

DETERMINATION  OF  LACTOSE 

Place  50  c.c.  of  the  mixed  copper  reagent  in  a  beaker  and  heat 
to  the  boiling  point.  While  boiling  briskly  add  100  c.c.  of  the  lactose 
solution  containing  not  more  than  0.300  gram  of  lactose  and  boil  for 
six  minutes.  Filter  impiediately  through  asbestos  and  wash.  Ob- 
tain the  weight  of  lactose  equivalent  to  the  weight  of  copper  found 
from  the  following  table. 


208 


Condensed  Milk  and  Milk  Powder 


"Table   for  the  Determination  of  Lactose    (Soxhlet-Wein)' 


Milli- 

Milli- 

Milli- 

Milli- 

Milli- 

Milli- 

Milli- 

Milli- 

Milli- 

Milli- 

grams 

grams 

grams 

grams 

grams 

grams 

grams 

grams 

grams 

grams 

of 

of 

of 

of 

of 

of 

of 

of 

of 

of 

copper 

lactose 

copper 

lactose 

copper 

lactose 

copper 

lactose 

copper 

lactose 

100 

71.6 

160 

116.4 

220 

161.9 

280 

208.3    1 

340 

253.7 

101 

72.4 

161 

117.1 

221 

162.7 

281 

209.1 

341 

256.5 

102 

73.1 

162 

117.9 

222 

163.4 

282 

209.9 

342 

257.4 

108 

73.8 

163 

118.6 

223 

164.2 

283 

210.7 

343 

258.2 

104 

74.6 

164 

119.4 

224 

164.9 

284 

211.5 

344 

259.0 

105 

75.3 

165 

120.2 

225 

165.7 

285 

212.3 

345 

259.8 

106 

76.1 

166 

120.9 

226 

166.4 

286 

213.1 

346 

2(50.6 

107 

76.8 

167 

121.7 

227 

167.2 

287 

213.9 

347 

261.4 

108 

77.6 

168 

122.4 

228 

167.9 

288 

214.7 

348 

262.3 

109 

78.3 

123.2 

229 

168.6 

289 

215.5 

349 

263.1 

110 

79.0 

170 

123.9 

230 

169.4 

290 

216.3 

350 

253.9 

111 

79.8 

171 

124.7 

231 

170.1 

291 

217.1 

3.51 

264.7 

112 

80.5 

172 

125.5 

232 

170.9 

292 

217.9 

352 

265.5 

113 

81.3 

173 

126.2 

233 

171.6 

293 

218.7 

353 

26S.3 

114 

82.0 

174 

127.0 

234 

172.4 

294 

219.5 

354 

267.2 

115 

82.7 

175 

127.8 

235 

173.1 

295 

220.3 

3.55 

268.0 

116 

176 

128.5 

236 

173.9 

296 

221.1 

356 

268.8 

117 

8412 

177 

129.3 

237 

174.6 

297 

221.9 

357 

269.6 

118 

85.0 

178 

130.1 

238 

175.4 

298 

222.7 

358 

270.4 

119 

85.7 

179 

130.8 

239 

176.2 

299 

223.5 

359 

271.2 

120 

86.4 

180 

131.6 

240 

176.9 

300 

224.4 

360 

272.1 

121 

87.2 

181 

132.4 

241 

177.7 

301 

225.2 

361 

272.9 

122 

87.9 

182 

133.1 

242 

178.5 

302 

225.9 

362 

273.7 

123 

183 

133.9 

243 

179.3 

303 

226.7 

363 

274.5 

124 

89!  4 

184 

134.7 

244 

180.1 

.304 

227.5 

364 

275.3 

125 

90.1 

185 

135.4 

245 

180.8 

305 

228.3 

365 

276.2 

126 

90.9 

186 

136.2 

246 

181.6 

306 

229.1 

366 

277.1 

127 

91.6 

187 

137.0 

247 

182.4 

307 

229.8 

367 

277.9 

128 

92.4 

188 

137.7 

248 

183.2 

308 

230.6 

368 

278.8 

129 

93.1 

189 

138.5 

249 

184.0 

3U9 

231.4 

369 

279.6 

130 

93.8 

190 

139.3 

250 

184.8 

310 

232.2 

370 

280.5 

131 

94.6 

191 

140.0 

251 

185.5 

311 

232.9 

371 

281.4 

132 

95.3 

192 

140.8 

252 

186.3 

312 

233.7 

372 

282.2 

13S 

96.1 

193 

141.6 

253 

187.1 

313 

234.5 

37S 

283.1 

134 

96.9 

194 

142.3 

254 

187.9 

314 

235.3 

374 

283.9 

135 

97.6 

195 

143.1 

255 

183.7 

315 

236.1 

375 

284.8 

136 

98.3 

196 

143.9 

256 

189.4 

316 

236.8 

376 

285.7 

137 

99.1 

197 

144.6 

257 

190  2 

317 

237.6 

377 

286.5 

138 

198 

145.4 

258 

191.0 

318 

238.4 

378 

287.4 

139 

100;5 

199 

146.2 

259 

191.8 

319 

239.2 

379 

288.2 

140 

101.3 

200 

146.9 

260 

192.5 

320 

240.0 

380 

289.1 

141 

102.0 

201 

147.7 

261 

193.3 

321 

240.7 

381 

2S9.9 

142 

102.8 

202 

148.5 

262 

194.1 

322 

241.5 

382 

290.8 

143 

•  103.5 

203 

149.2 

263 

194.9 

323 

242.3 

383 

291.7 

144 

104.3 

204 

150.0 

264 

195.7 

324 

243.1 

384 

292.5 

145 

105.1 

205 

150.7 

265 

196.4 

325 

243.9 

385 

293.4 

146 

105.8 

206 

151.5 

266 

197.2 

326 

244.6 

386 

294.2 

147 

106.6 

207 

152.2 

267 

198.0 

327 

245.4 

387 

295.1 

148 

107.3 

208 

153.0 

268 

198.8 

328 

246.2 

388 

236.0 

149 

108.1 

209 

153.7 

269 

199.5 

329 

247.0 

389 

2c)6.8 

150 

108.8 

210 

1.54.5 

270 

200.3 

330 

247.7 

390 

2?7.7 

151 

109.6 

211 

155.2 

271 

201.1 

331 

248.5 

391 

298.5 

152 

110.3 

212 

156.0 

272 

201.9 

332 

249.2 

392 

299.4 

153 

111.1 

213 

156.7 

273 

202.7 

333 

250.0 

393 

300.3 

154 

111.9 

214 

157.5 

274 

203.5 

334 

250.8 

394 

3J1.1 

155 

112.6 

215 

158.2 

275 

204.3 

335 

251.6 

39.-. 

302.0 

156 

113.4 

216 

159.0 

276 

205.1 

336 

252.5 

396 

302.8 

157 

114.1 

217 

159.7 

277 

205.9 

337 

253.3 

397 

308.7 

158 

114.9 

218 

160.4 

278 

206.7 

338 

254.1 

398 

304.6 

159 

115.6 

219 

161.2 

279 

207.5 

339 

1 

254.9 

400 

305.4 
306.3 

Condensed  Milk  and  Milk  Powder  209 

butter  fat 

The  Babcock  Test 
,staydard  glassware  1 

(a)  Standard  milk  test  bottles,  graduated  to  8  per  cent,  and 
with  sub-divisions  of  .1  per  cent. 

(b)  Pipette  graduated  to  17.6  c.c. 

(c)  Acid  measure  graduated  to  17.5  c.c. 

(d)  Centrifuge-Babcock  tester 

(e)  Water  bath  for  reading  at  135  to  140  degrees  F. 

(f)  Calipers  for  measuring  fat  column 

(g)  Sulphuric  acid,  specific  gravity  1.82  to  1.83 

DETERMIXATIOX 

Pipette  17.6  c.c.  of  the  properly  mixed  sample  of  milk  into  the 
milk  test  bottle.  Add  17.5  c.c.  of  acid  and  shake  until  all  the  curd 
is  completely  dissolved.  Both  milk  and  acid  should  have  a  temper- 
ature of  55  to  70  degrees  F.  If  milk  ajid  acid  are  too  warm,  sfet 
the  sample  bottles  and  the  acid  jar  into  a  trough  or  tub  of  water  at 
55  to  70  degrees  F.  for  thirty  minutes  before  testing.  The  test 
bottles  containing  the  mixture  of  milk  and  acid  are  then  whirled  in 
the  Babcock  tester  for  five  minutes  at  about  one  thousand  revolu- 
tions per  minute,  in  the  case  of  a  tester  with  a  twelve  inch  diameter 
wheel.  Fill  the  test  bottles  to  the  bottom  of  the  neck  with  hot 
water.  The  water  should.be  soft,  preferably  rain  water  or  distilled 
water.  If  hard  tap  water  is  used  it  should  be  boiled  to  precipitate 
the  carbonates,  otherwise  the  test  will  be  difficult  to  read,  owing  to 
the  presence  of  bubbles  of  gas  on  top  of  the  fat  column.  Revolve 
again  at  full  speed  for  two  minutes,  fill  the  test  bottles  to  near  the 
top  of  the  graduation  with  hot  water.  Whirl  in  the  centrifuge  for 
one  minute.  Now  set  the  test  bottles  in  the  water  bath  at  135  to 
140  degrees  F.  for  five  minutes.  The  test  is  now  ready  to  be  read. 
The  figures  on  the  test  bottles  represent  per  cent.  In  the  case  of 
the  8  per  cent,  standard  milk  test  bottle  the  sub-divisions  represent 
tenths  per  cent.  Read  from  the  bottom  of  the  lower  curve  to  the 
top  of  upper  curve  of  the  fat  column,  including  the  meniscus  in  the 
reading.- 


1  Hunziker,  Indiana  Agricultural  Experiment  Station,  Circulars  41  and  42,  1914 
-  For  correct  rea<iing  see  page  221 


210  Condensed  Milk  and  Milk  Powder 

GRAVIMETRIC  METHOD— PAPER  COIL 
"Make  coils  of  thick  filter  paper,  cut  into  strips  6.25  by  62.5 
cm.,  and  thoroughly  extract  with  ether  and  alcohol,  or  correct  the 
weight  of  the  extract  by  a  constant  obtained  for  the  paper.  From 
a  weighing  bottle  or  weighing  pipette,  transfer  about  5  grams  of 
milk  to  the  coil,  care  being  taken  to  keep  the  end  of  the  coil  held 
in  the  fingers,  dry.  Dry  the  coil,  dry  end  down,  on  a  piece  of  glass 
at  the  temperature  of  boiling  water ;  transfer  to  an  extraction  ap- 
paratus, and  extract  with  absolute  ether  or  petroleum  ether  boiling 
at  about  45  degrees  C. ;  dry  the  extracted  fat  and  weigh." 

SWEETENED  CONDENSED    MILK 


PREPARATION  OF  SAMPLE 

Pour  the  contents  of  the  can  into  a  bowl  or  on  a 
glass  plate.  Scrape  out  the  can  thoroughly,  removing 
all  the  sugar  sediment  from  the  top  and  bottom  of  the 
can.  Mix  thoroughly  with  pestle  or  spatula  until  a 
homogenous  emulsion  is  secured.  This  is  important, 
as  it  is  exceedingly  difficult  to  secure  a  representative 
sample  otherwise. 

If  it  is  desired  to  use  a  40  per  cent,  solution  as 
directed  in  the  determination  of  the  individual  ingred- 
ients, weigh  accurately  40  grams  of  the  properly  mixed 
contents  of  the  can  into  a  100  c.c.  graduated  flask. 
Add  60  c.c.  of  water.  The  sweetened  condensed 
milk  mixes  somewhat  difficultly  with  the  water. 
Complete  solution  is  facilitated  by  adding  the  water  in 
several  installments,  shaking  after  each  addition  un- 
til condensed  milk  sediment  adheres  no  longer  to  the  bottom  and 
sides  of  the  flask. 

SPECIFIC   GRAVITY 

Aerometric  Method,  by  Means  of  Beaume  Hydrometer 

APPARATUS 

Beaume  Hydrometer. — Use  a  specially  constructed  Beaume 
hydrometer  with  mercury  bulb,  and  a  scale  of  30  to  37  degrees  B., 
graduated  to  tenths  degrees.  Length  over  all,  twelve  inches ;  length 
of  spindel,  six  inches  ;  length  of  empty  bulb,  four  and  one-quarter 


Fig.  60.  Electric 
fat  extractor 

Courtesy  of 

E.  H.  Sargent 

&Co. 


Condensed  Milk  and  Milk  Powder         '  211 

inches;  width  of  empty  bulb,  thirteen-sixteenths  of  one  inch. 

Hydrometer  Jar. — Use  a  glass  or  tin  cyUnder  with  substantial 
base,  minimum  length  twelve  inches,  minimum  wddth  one  and  a  half 
inches. 

DETERMINATION 

The  Beaume  hydrometer  is  graduated  to  read  correctly  at  60 
degrees  F.  (15.5  degrees  C).  At  this  temperature  the  sweetened 
condensed  milk  is  too  viscous  for  rapid  and  accurate  work.  Warm 
the  condensed  milk  to  100  degrees  F.  or  above  and  correct  the 
Beaume  reading  by  adding  to  the  observed  reading  .025  points  for 
every  degree  Fahrenheit  above  60.  At  a  temperature  of  100  degrees 
F.  or  above,  the  reading  can  be  made  in  fifteen  minutes  or  less,  after 
the  hydrometer  is  inserted  in  the  milk. 

The  specific  gravity  is  determined  by  the  use  of  the  following 

formula : 

144.3 

Specific  gravity  = =- 

144-3 -B 

B  =  Beaume  reading  at  60  degrees  F. 
Example:    Observed  Beaume  reading  at  120  is  31.6 

Con-ected  reading  =:  31.6  +  [(120  -  60)  x  .025]  =  33.1 

144.3 

Specific  gravity      = r=  1.2077 

144-3 -33-1 

The  following  table  shows  the  specific  gravity  of  sweetened 
condensed  milk  when  the  Beaume  reading  is  known. 


212  Condensed  Milk  and  Milk  Powder 

Comparison  of  Degrees  Beaume  With  Specific  Gravity 


Beaume 

Specific 
gravity 

Beaume 

Specific 
gravity 

Beaume 

Specific 
gravity 

0 

1.000 

16.5 

1.130 

29.7 

1.260 

0.7 

1.005 

17.1 

1.135 

30.2 

1.265 

1.4 

1.010 

1.77 

1.140 

30.6 

1.270 

2.1 

1.015 

18.3 

1.145 

31.1 

1.275 

2.7 

1.020 

18.8 

1.150 

31.5 

1.280 

3.4 

1.025 

19.3 

1.155 

32.0 

1.285 

4.1 

1.030 

19.8 

1.160 

32.4 

1.290 

4.7 

1.035 

20.3 

1.165 

32.8 

1.295 

5.4 

1.040 

20.9 

1.170 

33.3 

1.300 

6.0 

1.045 

21.4 

1.175 

33.7 

1.305 

6.7 

1.050 

22.0 

1.180 

34.2 

1.310 

7.4 

1.055 

22.5 

1.185 

34.6 

1.315 

8.0 

1.060 

23.0 

1.190 

35.0 

1.320 

8.7 

1.065 

23.5 

1.195 

35.4 

1.325 

9.4 

1.070 

24.0 

1.200 

35.8 

1.330 

10.0 

1.075 

24.5 

1.205 

36.2 

1.335 

10.6 

1.080 

25.0 

1.210 

36.6 

1.340 

11.2 

1.085 

25.5 

1.215 

37.0 

1.345 

11.9 

1.090 

26.0 

1.220 

37.4 

1.350 

12.4 

1.095 

26.4 

1.225 

37.8 

1.355 

13.0 

1.100 

26.9 

1.230 

38.2 

1.360 

13.6 

1.105 

27.4 

1.235 

38.6 

1.365 

14.2 

1.110 

27.9 

1.240 

39.0 

1.370 

14.9 

1.115 

28.4 

1.245 

39.4 

1.375 

15.4 

1.120 

28.8 

1.250 

39.8 

1.380 

16.0 

1.125 

29.3 

1.255 

40.1 

1.385 

Gravimetric  Determination 

Dilute  a  measured  portion  of  a  40  per  cent,  solution  with  an 
equal  volume  of  water,  use  5  c.c.  of  the  diluted  mixture,  correspond- 
ing to  I  gram  of  the  condensed  milk  and  proceed  as  directed  under 
"Milk,"  page  201. 

TOTAL  SOLIDS 

Dilute  a  measured  portion  of  a  40  per  cent,  solution  with  an 
equal  volume  of  water,  measure  5  c.c.  of  the  diluted  mixture,  cor- 
responding to  I  gram  of  the  condensed  milk  into  an  evaporating 
dish  containing  15  to  20  grams  of  pure  dry  sand  and  proceed  as 
directed  under  "Milk,"  page  202. 

ASH 

Ignite  the  total  solids  at  very  low  redness,  cool,  and  weigh.  See 
"Milk,''  page  202. 


Condensed  Milk  and  Milk  Powder  213 

PRjOTEIDS 

Determine  nitrogen  in  5  c.c.  of  the  40  per  cent,  solution  accord- 
ing to  the  Gunning  method,  see  "Milk,"  page  202,  and  multiply  the 
results  by  6.38. 

LACTOSE 

Dilute  five  grams  of  a  40  per  cent,  solution  to  about  40  c.c.  and 
add  .6  c.c.  of  Fehling's  copper  solution.  Nearly  neutralize  with 
sodium  hydroxide,  make  up  to  100  c.c,  filter  through  dry  filter  and 
determine  lactose  in  an  aliquot  as  directed  under  "Milk — Determina- 
tion of  Lactose,"  page  204. 

FAT 

Modified  B.xbcock  Test 

Weigh  eighteen  grams,  or  measure  16.1  c.c.  of.  the  40  per  cent, 
solution  into  a  standard  Babcock  milk  test  bottle.  Add  4  c.c.  of 
commercial  sulphuric  acid,  specific  gravity  1.82  to  1.83.  Shake  im- 
mediately until  acid  is  thoroughly  mixed  with  the  milk.  Whirl  in 
Babcock  tester  for  six  minutes  at  full  speed.  The  centrifuge  must 
run  smoothly.  Stop  the  tester  gradually  and  remove  the  bottles 
carefully  so  as  not  to  break  the  layer  of  floating  curd.  Decant  the 
clear  whey  by  slowly  inclining  the  bottle.  Now  add  two-thirds  of 
a  17.6  c.c.  pipette  full  of  water.  After  thoroughly  shaking  to 
emulsify  the  curd  and  to  wash  it  free  of  sucrose,  add  4  c.c.  sulphuric 
acid,  shake,  whirl  and  decant  as  before.  Then  add  one  17.6  c.c. 
pipette  full  of  water,  17.5  c.c.  of  sulphuric  acid  and  complete  the 
Babcock  test  in  the  usual  way  as  directed  under  "Milk,"  page  209. 
Multiply  the  reading  by  2.5. 

This  method  yields  very  satisfactory  results  with  sweetened 
condensed  milk  containing  not  less  than  4  to  5  per  cent.  fat.  With 
condensed  milk  of  a  lower  fat  content  the  decanting  of  the  clear 
whey  is  difficult,  since  the  curd  in  the  partly  skimmed  product  is  too 
heavy  to  float  in  the  form  of  a  firm  cheese. 

The  Roese  Gottlieb  Method 

As  practiced  in  the  Dairy  Laboratory,  Bureau  of  Chemistry, 
Department  of  Agriculture 

"Weigh  out  4  to  5  grams  of  the  homogeneous  sample  of  con- 
densed milk  into  a  Rohrig  tube   (Zeit.  Unters  Nahr.  u.  Genussm, 


214  Condensed  Milk  and  Milk  Powder 

1905,  9:531)  or  some  similar  apparatus  and  dilute  with  water  in 
the  tube  to  about  10.5  c.c. — or,  if  preferred,  weigh  into  the  tube  10 
to  II  grams  of  a  40  per  cent,  solution  of  the  substance — add  134  c.c. 
of  concentrated  ammonium  hydroxid  (2  c.c.  if  the  sample  be  sour) 
and  mix  thoroughly  with  the  milk.  Add 
10  c.c.  of  95  per  cent,  alcohol  and  mix 
well.  Then  add  25  c.c.  of  washed  ethyl 
ether  and  shake  vigorously  for  half  a 
minute,  then  add  25  c.c.  of  petroleum 
ether  (redistilled  slowly  at  a  temperature 
below  60  degress  C.  preferably)  and 
shake  again  for  half  a  minute.  Let  stand 
Fig°°«i.  Balance  for  weighing  20  minutcs  or  uutil  the  Upper  liquid  is 
sweetened^condensed  milk  practically  clcar  and  its  own  lower  level 
The  Torsion  Balance  Co.  coustaut.  Draw  off  of  thc  ether  solution 
as  much  as  possible — usually  0.5  to  0.8  c.c.  will  be  left — into  a 
weighed  flask  through  a  diminutive  quick  acting  filter,  of  selected 
paper.  The  flask  should  always  be  weighed  with  a  similar  one  as 
counterpoise. 

"Re-extract  the  liquid  remaining  in  the  tube,  this  time  with 
only  15  c.c.  of  each  ether,  shaking  vigorously  half  a  minute  with 
each,  and  allow  to  settle. 

"Draw  ofif  the  clear  solution  through  the  small  filter  into  the 
same  flask  as  before  and  wash  the  tip  of  the  spigot,  the  funnel  and 
the  filter  with  a  few  c.c.  of  a  mixture  of  the  two  ethers  in  equal  parts 
(previously  mixed  and  free  from  deposited  water). 

"For  perfectly  exact  results  the  re-extraction  must  be  repeated. 
This  extraction  yields  usually  not  more  than  about  a  milligram  of 
fat,  if  the  previous  ether-fat-solutions  have  been  drawn  off  closely 
— an  amount  averaging  about  .02  per  cent,  on  a  4  gram  charge. 

"Evaporate  the  ether  slowly  on  a  steam  bath,  then  dry  the  fat 
in  a  boiling  water  oven  until  loss  of  weight  ceases. 

"Prove  the  purity  of  the  fat  by  dissolving  in  a  little  petroleum 
ether.  Should  a  residue  remain,  wash  the  fat  out  completely  with 
petroleum  ether,  dry  the  residue,  weigh,  and  deduct  the  weight. 
(This  should  not  often  be  necessary.) 

"Finally  deduct  the  weight  obtained  by  blank  determination  on 
the  chemicals  used. 

"By  this  method  practically  absolute  results  can  be  obtained." 


Condensed  Milk  and  Milk  Powder  215 

SUCROSE 

Determine  by  difference,  deducting  the  milk  solids   (ash  plus 

proteids  plus  lactose  plus  fat)   from  the  total  solids,  or  invert  the 

sucrose,   determine  the   total   invert   sugar,   deduct   from  this  the 

lactose  calculated  as  invert   sugar  and  calculate  the   difference  as 

sucrose. 

MILK  SOLIDS 

Deduct   the   per  cent,   sucrose   from  the   percent,   total   solids. 

The  dift'erence  represents  the  per  cent,  milk  solids. 

EVAPORATED  MILK 
PREPARATION  OF  SAMPLE 

Shake  the  can  of  evaporated  milk  vigorously  before  opening. 
If,  upon  opening  the  can,  separated  cream  or  small  lumps  of  butter 
are  found  to  adhere  to  the  seams  and  around  the  junction  of  the 
ends  and  the  body,  set  the  can  in  a  water  bath  at  130  degrees  F.  for 
ten  minutes  or  until  all  fat  is  completely  dissolved.  Then  pour  the 
entire  contents  into  a  beaker  and  pour  back  and  forth  several  times 
until  a  homogeneous  mixture  is  secured.  If  it  is  known  before 
opening  the  can  that  the  contents  are  separated,  submerge  the  whole 
can  in  a  water  bath  at  130  degrees  F.  for  ten  minutes,  then  shake, 
open  and  proceed  as  above. 

If  it  is  desired  to  use  a  40  per  cent,  solution,  as  directed  under 
the  determination  of  the  individual  ingredients,  weigh  accurately 
40  grams  of  the  properly  mixed  contents  of  the  can  into  a  100  c.c. 
graduated  flask.  Add  60  c.c.  water  and  mix  thoroughly  by  shaking 
or  stirring. 

SPECIFIC    GRAVITY 

Aerometric   Method 

APPARATUS 

Beaunic  hydrometer. — Use  a  special  Beaume  hydrometer  with 
a  scale  ranging  from  five  to  twelve  points,  graduated  to  tenths  de- 
grees and  mercury-weighted.  Length  over  all  eleven  inches,  length 
of  spindel  six  inches,  length  of  empty  bulb  four  inches  and  width 
of  empty  bulb  seven-eighths  inch. 

Hydrometer  jar. — Use  a  glass  or  tin  cylinder  with  substantial 
base.  Minimum  height  ten  inches  and  minimum  width  one  and  a 
half  inches. 


2i6  Condensed  Milk  and  Milk  Powder 

DETERMIXATIOX 

The  Beaume  hydrometer  is  graduated  to  read  correctly  at  6o 
degrees  F.  (15.5  degrees  C).  For  every  degree  Fahrenheit  above 
60  add  .0313  points  to  the  observed  reading.  For  every  degree 
Fahrenheit  below  60,  deduct  .0313  points  from  the  observed  reading. 

The  specific  gravity  is  determined  by  the  use  of  the  following 

,  formula : 

,.       .,  .  145-5 

Specific  gravity  =  ^ 

145-5  — t5 

B  =  Corrected  Beaume  reading 
Example :     Beaume  reading  at  80  degrees  F.  is  7.8 

Corrected  reading  =  7.8  -^  [(80  —  60)  x  .0313]  =  8.43 


Specific   gravity   =  o =    1.06 r 

-  145-5  — ^"^-43 


Equally  good  results  may  be  obtained  by  diluting  the  evapo- 
rated milk  with  an  equal  weight  of  water.  Then  take  the  Quevenne 
lactometer  reading  at  60  degrees  F.  Multiply  the  reading  by  2, 
add  1000,  and  divide  by  1000. 

Gravimetric  Determination 
Dilute  the  evaporated  milk  with  four  times  its  weight  of  water 
and  proceed  as  directed  under  "Milk,"  page  201. 

TOTAL   SOLIDS 

By  Means  of  Specific  Gravity  and  Babcock  Formula 
Determine  the  specific  gravity  as  above  directed.     Multiply  by 
1000  and  subtract  1000.     Then  use  the  following  formula : 

L 

+  1 . 2  X  f 

4 

L  =  The  figure  derived  from  the  specific  gravity  by  above  cal- 
culations 

f  =  per  cent,  fat 

Example :  Evaporated  milk  tests  7.8  per  cent,  fat  and  has  a 
specific  gravity  of  1.0615 

L  =  (1.0615  X  1000)  —  1000  =  61.5 

61.5 
Total  solids  = +1.2x7.8  =  24.74  per  cent. 


Condensed  Milk  and  Milk  Powder  217 

For  rapid  determination  of  the  total  solids  of  evaporated  milk 
the  factory  operator  is  referred  to  the  following  tables  from  which 
the  per  cent,  total  solids  may  be  read  at  a  glance  when  the  Beaume 
reading  at  60  degrees  F.  and  the  per  cent,  fat  are  known. 

PER  CENT.   SOLIDS   OF    EVAPORATED    MILK 
The  Beaume  Degrees  at  60  Degrees  F.  are  Indicated  in  the  Horizon- 
tal Line  at  the  Top.    The  Per  Cent,  of  Fat  is  Shown  in 
the  A'ertical  Column  at  the  Left 


Beaume  reading  at  60  degrees  Fahrenheit 

FAT 

PER 

CENT 

8.0        8.1     1 

8.2 

8.3 

8.4 

8.5 

8.6 

8.7 

8.8 

8.9 

Solids 
per 
cent. 

Solifls 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
ceat. 

1 

60 

2175 

21.94 

22.13 

?2.32 

22.52 

22.71 

22.90 

23.10 

23.29 

23.49 

G2 

2199 

22.18 

22.37 

22  56 

22.76 

.22.95 

23.14 

23.34 

23.53 

23.73 

()  4 

22  23 

22  42 

22.(U 

22.80 

23.00 

23.19 

23.38 

23  58 

23.77 

23.97 

6f) 

22  47 

22.(i(i 

22.S5 

23  04 

23.24 

23.43 

23.62 

23.82 

24.01 

24.21 

G.8 

22.71 

22.!in 

23.(1!) 

23.28 

23.48 

23.67 

23.86 

24.06 

24.25 

24.45 

70 

22  95 

23.14 

23.33 

23.52 

23.72 

23.91 

24.10 

24.30 

24.49 

24.69 

7  2 

2319 

23  38 

23.57 

23.76 

23.96 

24.15 

24.34 

24.54 

24.73 

24.93 

74 

23  43 

23.62 

23.81 

24  00 

24.20 

24.39 

24.58 

24.78 

24.97 

25.17 

76 

23  67 

23.86 

24.05 

24.24 

24.44 

24.63 

24.82 

25.02 

25.21 

25.41 

7.8 

23.91 

24.10 

24.29 

24.48 

24.(i8 

24.87 

25.06 

25.26 

25.45 

25.65 

80 

2415 

24.34 

24.53 

24  72 

24.92 

25.11 

25.30 

25..50 

25.69 

25.89 

82 

24.39 

24.58 

24.77 

24.96 

25.16 

25.35 

25.54 

25.74 

25.93 

26.13 

84 

24  63 

24.82 

25.01 

25.20 

25.40 

25.59 

2.5.78 

25.98 

26.17 

26.37 

86 

24.87 

25.06 

25.35 

25.44 

25.64 

25.83 

26.02 

26.22 

26.41 

26.61 

8.8 

25.11 

25.30 

25.49 

25.68 

25.88 

26.07 

26.26 

26.46 

26.65 

26.85 

90 

25.35 

25.54 

25.73 

25.92 

26.12 

26.31 

26.50 

26.70 

26.89 

27.09 

92 

25.59 

25.78 

25.97 

2(;.i(i 

26.36 

2(i.55 

26.74 

26.94 

27.13 

27.33 

9.4 

25.83 

26.02 

26.21 

26.40 

26.(;0 

2li.7.'» 

26.98 

27.18 

27.37 

27.57 

96 

26.07 

26.26 

26.45 

26,64 

2(184 

27.03 

2V.22 

27.42 

27.61 

27.81 

9.8 

26.31 

26.50 

26.69 

26.88 

27.08 

27.27 

27.46 

27.66 

27.85 

28.05 

10  0 

26.55 

26.74 

26.93 

27,12 

27.32 

27.51 

27.70 

27.90 

28.09 

28.29 

lO'-* 

2()  7!) 

2(;.!)S 

27.17 

27,36 

27.56 

27.75 

27.94 

28.14 

28.33 

28.53 

10.4 

27.1)3 

•;7  •)•) 

27.41 

27.60 

27.80 

27.99 

28.18 

28  38 

28.57 

28.77 

10  6 

27  27 

27.46 

27.65 

27,84 

28.04 

28.23 

28.42 

28.62 

28.81 

29.01 

10.8 

27.51 

27.70 

27.89 

28.08 

28.28 

28.47 

28.66 

28.86 

29.05 

29.25 

11  0 

27  75 

27.94 

28.13 

28  32 

28.52 

28.71 

28.90 

29.10 

29.29 

29.49 

11.2 

27.99 

28.18 

28.37 

28,56 

28.76 

28.95 

29.14 

29.34 

29.-58 

29.73 

11  4 

28.23 

28.42 

28.61 

28.80 

29.01) 

29.19 

29.38 

29.58 

29.77 

29.97 

11  6 

28  47 

28.66 

28.85 

29.04 

29.24 

29.43 

29.62 

29.82 

30.01 

30.21 

11.8 

28.71 

28.90 

1 

29.09 

29.28 

29.48 

29.67 

29.86 

30.06 

30,25 

30.45 

2l8 


Condensed  Milk  and  Milk  Powder 


PER   CENT.  SOLIDS  OF    EVAPORATED   MILK    (Continued) 

The  Beaume  Degrees  at  60  Degrees  F.  arc  Indicated  in  the  Horizon- 
tal Line  at  the  Top.    The  Per  Cent,  of  Fat  is  Shown 
in  the  Vertical  Column  at  the  Left 


Beaume  reading  at  60  degrees  Fahrenheit 

9.0 

9.1 

9.2 

9.3 

9.4 

9.5 

9.6 

9.7 

9.8 

9.9 

FAT 

PER 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

CENT 

per 

per 

per 

per 

per 

per 

per 

per 

per 

per 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

6.0 

23.68 

23.88 

24.08 

24.27 

24.47 

24.66 

24.86 

25.06 

25.26 

25.45 

6.2 

23.92 

24.12 

24.32 

24.51 

24.71 

24.90 

25.10 

25.30 

25.50 

25.69 

6.4 

24.16 

24.36 

24.56 

24.75 

24.95 

25.14 

25.34 

25.54 

25.74 

25.93 

6.6 

24.40 

24.60 

24.80 

24.99 

25.19 

25.38 

25.58 

25.78 

25.98 

26.17 

6.8 

24.64 

24.84 

25.04 

25.23 

25.43 

25.62 

25.82 

26.02 

26.22 

26.41 

7.0 

24.88 

25.08 

25.28 

25.47 

25.67 

25.86 

26.06 

26.26 

26.46 

26.65 

7.2 

25.12 

25.32 

25.52 

25.71 

25.91 

26.10 

26.30 

26.50 

26.70 

26.89 

7.4 

25.36 

25.56 

25.76 

25.95 

26.15 

26.34 

26.54 

26.74 

26.94 

27.13 

7.6 

25.60 

25.80 

26.00 

26.19 

26.39 

26.58 

26.78 

26.98 

27.18 

27.37 

7.8 

25.84 

26.04 

26.24 

26.43 

26.63 

26.82 

27.02 

27  22 

27.42 

27.61 

8.0 

26.08 

26.28 

26.48 

26.67 

26.87 

27.06 

27.26 

27.46 

27.66 

27.85 

8.2 

26.32 

26.52 

26.72 

26.91 

27.11 

27.30 

27.50 

27.70 

27.90 

28.09 

8.4 

26.56 

26.76 

26.96 

27.15 

27.35 

27.54 

27.74 

27.94 

28.14 

28.33 

8.6 

26.80 

27.00 

27.20 

27.39 

27.59 

27.78 

27.98 

28.18 

28.38 

28.57 

8.8 

27.04 

27.24 

27.44 

27.63 

27.83 

28.02 

28.22 

28  42 

28.()2 

28.81 

9.0 

27.28 

27.48 

27.68 

27.87 

28.07 

28.26 

28.46 

28.66 

28.86 

29.05 

9.2 

27.52 

27.72 

27.92 

28.11 

28.31 

28.50 

28.70 

28.90 

29.10 

29.29 

9.4 

27.76 

27.96 

28.16 

28.35 

28.55 

28.74 

28.94 

29.14 

29.34 

29.53 

9.6 

28.00 

28.20 

28.40 

28.59 

28.79 

28.98 

29.18 

29.38 

29.5  S 

29.77 

9.8 

28.24 

28.44 

28.64 

28.83 

29.03 

29.22 

29.42 

29.62 

29.82 

30.01 

10.0 

28.48 

28.68 

28.88 

29.07 

29.27 

29.46 

29.66 

29.86 

30.06 

30.25 

10.2 

28.72 

28.92 

29.12 

29.31 

29.51 

29.70 

29.90 

30.10 

30.30 

£0.49 

10.4 

28.96 

29.16 

29.36 

29.55 

29.75 

29.94 

30.14 

30.34 

30.54 

30.73 

10.6 

29.20 

29.40 

29.60 

29.79 

29.99 

30.18 

30.3  B 

30  58 

30.78 

30.97 

10.8 

29.44 

29.64 

29.84 

30.03 

30.23 

30.42 

30.62 

3(182 

31.02 

31.21 

11.0 

29.68 

29.88 

30.08 

30.27 

30.47 

30.66 

30.86 

31.06 

31.26 

31.45 

11.2 

29.92 

30.12 

30.32 

30.51 

30.71 

30.90 

31.10 

31.30 

31.c0 

31.69 

11.4 

30.16 

30.36 

30.56 

30.75 

30.95 

31.11 

3134 

31.54 

31.74 

31.93 

11.6 

30.40 

30.60 

30.80 

30.99 

31.19 

31.38 

3158 

31.78 

31.98 

32.17 

11.8 

30.64 

30.84 

31.04 

31.23 

31.43 

31.62 

31.82 

32.02 

3222 

32  41 

Condensed  Milk  and  Milk  Powder 


219 


PER   CENT.   SOLIDS   OF    EVAPORATED    MILK    (Continued) 

The  Beaume  Degrees  at  60  Degrees  F.  are  Indicated  in  the  Horizon- 
tal Line  at  the  Top.    The  Per  Cent,  of  Fat  is  Shown 
in  the  Vertical  Column  at  the  Left 


Beaume 

reading  at  60  degrees  Fahrenheit 

10.0 

10.1 

10.2 

10.3 

10.4 

10.5 

10.6 

10.7 

10.8 

10.9 

FAT 

PER 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

Solids 

CENT 

per 

per 

per 

per 

per 

per 

per 

per 

per 

per 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

6.0 

25.65 

25.85 

26.05 

26.25 

26.45 

26.65 

26.85 

27.05 

27.25 

27.45 

6.2 

25.89 

26.09 

26.29 

26.49 

26.69 

26.89 

27.09 

27.29 

27.49 

27.69 

6.4 

26.13 

26.33 

26.53 

26.73 

26.93 

27.13 

27.33 

27.53 

27.73 

27.93 

6.6 

26.37 

26.57 

26.77 

26.97 

27.17 

27.37 

27.-57 

27.77 

27.97 

28.17 

6.8 

26.61 

26.81 

27.01 

27.21 

27.41 

27.61 

27.81 

28.01 

28.21 

28.41 

7.0 

26.85 

27.05 

27.25 

27.45 

27.65 

27.85 

28.05 

28.25 

28.45 

28.65 

7.2 

27.09 

27.29 

27.49 

27.69 

27.89 

28.09 

28.29 

28.49 

28.69 

28.89 

7.4 

27.33 

27.53 

27.73 

27.93 

28.13 

28.33 

28.53 

28.73 

28.93 

29.13 

7.6 

27.57 

27.77 

27.97 

28.17 

28.37 

28.57 

28.77 

28.97 

29.17 

29.37 

7.8 

27.81 

28.01 

28.21 

28.41 

28.61 

28.81 

29.01 

29.21 

29.41 

29.61 

8.0 

28.05 

28.25 

28.45 

28.65 

28.85 

29.05 

29.25 

29.45 

29.65 

29.85 

8.2 

28.29 

28.49 

28.69 

28.89 

29.09 

29.29 

29.49 

29.()9 

29.89 

30.09 

8.4 

28.53 

28.73 

28.93 

29.13 

29.33 

29.53 

29.73 

29.93 

30.13 

30.33 

8.6 

28.77 

28.97 

29.17 

29.37 

29.57 

29.77 

29.97 

30.17 

30.37 

30.57 

8.8 

29.01 

29.21 

29.41 

29.61 

29.81 

30.01 

30,21 

30.41 

30.61 

30.81 

9.0 

29.25 

29.45 

29.65 

29.85 

30.05 

30.25 

30.45 

30.65 

30.85 

31.05 

9.2 

29.49 

29.69 

29.89 

30.09 

30.29 

30.49 

30.69 

30.89 

31.09 

31.29 

9.4 

29.73 

29.93 

30.13 

30.33 

30.53 

30.73 

30.93 

31.13 

31.33 

31..53 

9.6 

29.97 

30.17 

30.37 

30.57 

30.77 

30.97 

31.17 

31.37 

31.57 

31.77 

9.8 

30.21 

30.41 

.30.61 

30.81 

31.01 

31.21 

31.41 

31.61 

31.81 

32.01 

10.0 

30.45 

30.65 

30.85 

31.05 

31.25 

31.45 

31.65 

3L85 

32.05 

32.25 

10.2 

30.69 

30.89 

31.09 

31.29 

31.49 

31.69 

31.89 

32.09 

32.29 

32.49 

10.4 

30.93 

31.13 

31..33 

31.53 

31.73 

31.93 

32.13 

32.33 

32.-53 

32.73 

10.6 

.31.17 

31.37 

31. .57 

31.77 

31.97 

32.17 

32.37 

32.57 

32.77 

32.97 

10.8 

31.41 

31.61 

31.81 

32.01 

32.21 

32.41 

32.61 

32.81 

33.01 

33.21 

11.0 

31.65 

31.85 

.32.05 

32.25 

32.45 

32.65 

32.85 

33.05 

33.25 

-33.45 

11.2 

31.89 

32.09 

32.29 

32.49 

32.69 

32.89 

33.09 

33.29 

33.49 

33.69 

11.4 

32.13 

32.33 

32.53 

.32.73 

32.93 

.3.3.13 

33.33 

33.53 

33.73 

33.93 

11.6 

32.37 

32.57 

32.77 

32.97 

33.17 

33.37 

33.57 

33.77 

33.97 

34.17 

11.8 

32.61 

32.81 

33.01 

33.21 

33.41 

33.61 

33.81 

34.01 

34.21 

34.41 

220  Condensed  Milk  and  Milk  Powder 

Gravimetric  Determination 

Dilute  a  measured  portion  of  a  40  per  cent,  solution  with  an 
equal  volume  of  water,  use  5  c.c.  of  the  diluted  mixture,  correspond- 
ing to  I  gram  of  the  evaporated  milk  and  proceed  as  directed  under 
"Milk,"  page  202. 

ASH 

Ignite  the  total  solids  at  very  low  redness,  cool,  and  weigh,  see 
"Milk,"  page  202. 

PROTEIDS 

Use  5  c.c.  of  a  40  per  cent,  solution,  determine  nitrogen  ac- 
cording to  the  Gunning  Method  as  directed  under  "Milk,"  page  202, 
and  multiply  result  by  6.38. 

LACTOSE 

Dilute  10  grams  of  a  40  per  cent,  solution  to  about  40  c.c.  and 
add  .6  c.c.  of  Fehling's  copper  solution ;  nearly  neutralize  with  so- 
dium hydroxide,  make  up  to  100  c.c,  filter  through  dry  filter,  and 
determine  lactose  in  an  aliquot  as  directed  under  "Milk,"  page  204. 

FAT 
The  Modified  Babcgck  AIethod^ 
Carefully  weigh  4.5  grams  of  well-mixed  evaporated  milk  into 
the  8  per  cent,  test  bottle.  Add  one  17.6  pipetteful  of  water.  Add 
17.5  c.c.  of  sulphuric  acid  and  shake  until  the  curd  in  the  test  bottle 
is  completely  dissolved.  Whirl  at  usual  speed  (one  thousand  revo- 
lutions per  minute )  for  five  minutes.  Mix  equal  portions  of  water 
and  sulphuric  acid  in  glass  beaker.  For  one  or  two  tests,  one 
pipetteful  of  water  and  one  acid  measure  full  of  acid  are  sufficient. 
Fill  test  bottle  to  slightly  below  the  bottom  of  the  neck  with  the  hot 
diluted  acid.  Whirl  for  two  minutes.  If  the  fat  collected  at  the 
base  of  the  neck  is  not  clear,  shake  the  bottles  until  all  the  curdy 
matter  is  completely  dissolved,  fill  bottle  to  about  the  8  per  cent, 
mark  with  hot  water,  whirl  for  one  minute  and  read  the  test  at  140 
degrees  F.  The  fat  column  must  be  read  from  the  top  of  the  upper 
meniscus  to  the  bottom  of  the  lower  meniscus.  Multiply  the  reading 
by  4.    This  gives  the  correct  per  cent,  of  fat. 


Hunziker  and  Spitzer,  Indiana  Agricultural  Experiment  Station,  Bulletin  No.  134,  1909 


CoNDiiNSED  Milk  axd  Milk  Powder 


Instead  of  weighing  4.5  grams  into  the  test  bottle,  a  4.3  c.c. 
pipette  may  be  used.     After  emptying  the  pipette  into  the  bottle  it 

should  be  rinsed  twice,  and  the  rins- 
ings discharged  into  the  test  bottle. 
For  making  numerous  tests 
from  the  same  sample  it  is  advis- 
able to  dilute  the  evaporated  milk 
with  equal  parts  of  water,  by 
weight ;  then  weigh  nine  grams  of 
this  dilution  into  the  test  bottles  and 
add   one-half   pipetteful  of   water. 


-B 


Read  from  A  to  D 


KeailiiiK  the  lialti-t 


The  Roese  Gottlieb  Method 

Proceed  as  directed  under 
"Sweetened  Condensed  Milk,"  page 
213. 

MILK    POWDER 
TOTAL   SOLIDS 

Weigh  5  grams  of  the  milk 
powder  in  a  drying  bottle  or  evap- 
orating dish  and  place  in  drying 
oven  at  100  to  105  degrees  C.  until 
constant  weight  is  secured. 

ASH 


\\'eigh  two  grams  of  the  milk  powder  in  a  weighed  platinum 
dish  and  proceed  as  directed  under  "Milk,"  page  202. 

PROTEIDS 

Use  5  grams  of  the  milk  powder  and  proceed  as  directed  under 
"Milk,"  page  202. 

MILK  SUGAR   (LACTOSE) 

Dissolve  10  grams  of  milk  powder  in  90  c.c.  of  water.  Warm 
and  stir  until  a  satisfactory  solution  is  effected  and  proceed  as 
di/ected  under  "Milk,"  page  204,  and  multiply  result  by  10. 

SUCROSE 
For  the  determination  of   sucrose  proceed  as   directed  under 
"v'^weetened  Condensed  Milk,"  page  215. 


222  Condensed  Milk  and  Milk  Powder 

FAT 

The  Babcock  Test  Method.— Dissolve  lo  grams  of  milk 
powder  in  90  c.c.  of  water.  Warm  and  mix  until  a  complete  solu- 
tion is  effected.  Then  proceed  as  directed  under  "Milk,"  page  209, 
and  multiply  the  result  by  10. 

"Roe:se  Gottlieb  Method. — Weigh  i  gram  of  the  powder  in 
a  30  c.c.  lipped  beaker.  Rub  up  with  9  c.c.  of  water  and  2  c.c.  of 
concentrated'  ammonium  hydroxid,  digest  on  steam  bath  until  the 
casein  is  well  softened  and  the  whole  resembles  milk.  Cool,  transfer 
to  Rohrig  tube  or  similar  apparatus,  using  10  c.c.  of  95  per  cent, 
alcohol  for  rinsing,  followed,  after  shaking  contents  of  tube,  by  25 
c.c.  of  washed  ethyl  ether.  Shake  vigorously  for  one-half  minute, 
and  proceed  as  in  the  determination  of  fat  in  sweetened  condensed 
milk." 

CHAPTER  XXXI 

DETECTION    OF    ADULTERANTS    AND    PRESERVATIVES 
IN  MILK 

Addition  of  Water  and  Skim  Milk  and  the  Removal  of  Cream 

Frequency  of  Adulteration. — Experience  has  shown  that 
where  milk  is  received  from  a  large  number  of  patrons,  as  is  the 
case  in  most  milk  condensing  factories,  some  of  the  milk  may  be  and 
frequently  is  being  tampered  with  before  it  reaches  the  factory. 
In  the  case  of  condenseries  buying  and  paying  for  the  milk  on  the 
butter  fat  basis,  neither  the  watering  nor  the  skimming  of  the  milk 
results  in  any  material  direct  loss  to  the  factory.  Excessive  skim- 
ming, however,  does  reduce  the  yield  of  the  finished  product  some- 
what, inasmuch  as  a  small  amount  of  solids  is  removed  with  the 
cream.  Excessive  watering  necessitates  the  expenditure  of  slightly 
more  fuel  to  remove  the  extraneous  water  in  the  process  of  evap- 
oration. 

Where  the  condensery  buys  and  pays  for  its  milk  by  the  hun- 
dred weight,  however,  it  is  obviou.sly  essential  that  such  adultera- 
tions be  guarded  against  by  eternal  vigilence. 

Taking  and  PresivRvtng  of  the  Sample. — In  order  to  mini- 
mize the  work  of  testing  without  interfering  with  the  effectiveness 


CoNDENSKD  Milk  and  Milk  Powder  223 

of  the  control,  it  is  advisable  to  take  composite  samples.  Use  pint 
jars  with -tight  lids;  label  the  jars  with  the  number  of  the  respective 
patron  and  place  them  in  numerical  order  on  conveniently  located 
shelves  on  the  receiving  platform.  In  the  case  of  the  route  system 
of  receiving  milk,  the  samples  of  milk  from  each  route  should  be 
stored  together.  Use  a  dipper  holding  one  ounce  of  milk  ;  by  pour- 
ing a  dipperful  of  milk  of  each  patron  each  day  into  the  respective 
jars,  enough  milk  is  collected  in  each  jar  at  the  end  of  two  weeks 
to  test  with  the  lactometer  and  the  Babcock  test  every  two  weeks. 

In  order  to  preserve  the  samples  in  proper  condition  drop  a 
large  corrosive  sublimate  tablet  into  each  empty  jar  and  after  each 
addition  of  milk,  mix  the  corrosive  sublimate  with  the  milk  by  giv- 
ing the  jar  a  rotary  motion.  Add  one  dipperful  of  each  patron's 
milk  daily  into  the  jars. 

Testing  the  Composite  Samples. — At  the  end  of  every  two 
weeks  test  the  samples  with  the  Quevenne  lactometer  and  the  Bab- 
cock test.  The  samples  should  have  a  temperature  of  55  to  65  de- 
grees F.  In  summer  and  at  any  other  time  when  the  temperature 
naturally  is  much  higher  or  lower,  place  the  sample  jars  into  a  tank 
or  tub  of  water  at  the  desired  temperature,  from  one  half  hour  to 
an  hour  before  testing.  For  directions  for  the  use  of  the  lactom- 
eter and  the  Babcock  tester,  see  Chapter  XXX,  "Milk,"  page  200. 
If  the  milk  contains  corrosive  sublimate,  deduct  one-half  point  from 
the  lactometer  reading  for  each  tablet  in  one  pint  of  sample. 

Interpretation  of  Results. — The  lactometer  reading  and  the 
l)er  cent,  fat  alone  furnish  a  pretty  safe  index  to  the  freedom  from, 
or  presence  of  adulteration  of  the  milk.  From  these  two  factors 
other  guides,  such  as  the  specific  gravity,  per  cent,  of  total  solids 
and  per  cent,  of  solids  not  fat  of  milk,  and  specific  gravity  of  the 
milk  solids  may  be  calculated.  These  are  of  additional  assistance  to 
the  inspector.  All  of  these  factors  vary  considerably  with  the  indi- 
viduality, breed,  period  of  lactation  and  feed  of  the  cows,  so  that 
considerable  latitude  must  be  allowed  in  determining  whether  or  not 
any  given  sample  of  milk  has  been  a(lulterate<l.  These  variations  arc 
greatest  between  individual  cows  and  between  different  breeds,  but 
they  also  are  quite  striking  in  milk  of  the  same  cows  from  day  to  day 
and  at  dififerent  stages  of  the  period  of  lactation.  In  mixed  herd 
milk,  such   as  the  condensery  largely  receives,   the   composition   is 


224 


Condensed  Milk  and  Milk  Powder 


comparatively  uniform  on  consecutive  days.  Whenever  possible, 
in  the  case  of  suspicious  milk  received  at  the  factory,  samples 
should  be  secured  direct  from  the  stable  for  comparison. 

The  following  may  be  considered  reasonable  limits  of  compo- 
sition beyond  which  normal  milk  seldom  trespasses,  and  milk  not 
falling  within  these  limits  may  be  regarded  with  suspicion. 


Minimum       ^Maximum 

Fat  2.5    per  cent. 

Specific  gravity  of  milk  1.029  1034 

Per  cent,  total  solids  11.50 

Per  cent,  solids  not  fat  7.75  9.25 

Specific  gravity  of  milk 

solids  1.25  1.36 


Average 

4      per  cent. 
1.032 
12.3 

8.5 

1-33 


These  factors  are  affected  by  the  skimming  and  watering  of 
milk  as  follows : 


Cream  removed  or 
skim  milk  added 


Fat  low 

Specific  gravity  of  milk  high 

Total  solids  loiv 

Solids  not  fat  high 

Specific  gravity  of  milk  solids  high 


\\'ater  added 


Fat  normal  or  low 

Specific  gravity  of  milk  low 

Total  solids  low 

Solids  not  fat  loiv 

Specific  gravity  of  milk  soli<ls  normal 


Cream  removed 
and  water  added 


Fat  loiv 

Specific  gravity  of  milk  nonua! 

Total  solids  lozv 

Solids  not  fat  lox^'  or  nonnal 

Specific  gravity  of  milk  solids  nonnal  or  high 

The  total  solids  are  determined  bv  the  formula 


+  I.2X  f 


Condensed  Milk  and  Milk  Powder  225 

The  solids  not  fat  are  determined  by  the  formula 

L 

+  .2  X  f 

4 

The   specific  gravity  of   the  milk  solids  is  determined  by  the 

formula 

t 

t-  lOOs-  100 


s 

L  =  Ouevenne  lactometer  reading  at  60  degrees  F. ;  f  =  per 
cent,  fat ;  t  =  total  solids ;  s  =  specific  gravity  of  milk. 

Example  of  milk  that  is  normal. — Ouevenne  lactometer  reading 
at  60  degrees  F.  32,  fat  4  per  cent. 

Answer : 

Specific  gravity  of  the  milk  =:   1.032 

32 

Total  solids  +  1.2  x  4  =  12.8  per  cent. 

4 

32 

Solids  not  fat  +  .2x4=:  8.8  per  cent. 

4 

Specific  gravity  of  milk  solids 
12.48 


12.48  -  100  X  1.032  -  100  =  1.33 
1 .032 

Example  of  milk  to  ichicli  water  has  been  added. — Ouevenne 
lactometer  reading  at  C)0  degrees  F.  26,  fat  3.8  per  cent. 
Answer : 

Specific  gravity  of  milk  =  1.026 

26 

Total  solids +  1.2  x  3.8  =  11.06  per  cent. 

4 

26 
Solids  not  fat   +  .2  x  3.8  =  7.26  per  cent. 

4 

Specific  gravity  of  milk  solids 
11.06 


I  1.06  -  100  X  1.026  -   TOO  =    1-295 

1.026 


226  Condensed  Milk  and  Milk  Powder 

Example  of  milk  from  which  cream  zvas  removed  or  to  ivhich 
skimmed  milk  zvas  added. — Quevenne  lactometer  reading  at  60  de- 
grees F.  35,  fat  2  per  cent. 

Answer : 

Specific  gravity  of  milk  =  T.035 

35 


Total 

solid 

Is  — 
4 

— h 

1.2  X  2  = 

II. 

15  per 

cent. 

Solid; 

5  not 

fat  - 

35^ 

4 

+  .2x2  = 

9. 

15  per 

cent. 

Speci 

fie  gravity 

of 

milk  solids 

•15- 

II 

•15 

=  1 

•44^' 

II 

100  X  I.( 

035  -  100  = 

I -035 

Example  of  milk  from  ivhkh  cream  z^'as  rcuiovcd  and  to  ■K'liich 
water  was  added. — Quevenne  lactometer  reading  at  60  degrees  F. 
32,  fat  2  per  cent. 

Answer : 

Specific  gravity  of  milk  ==  1.032 

32 

Total  solifls +  1.2  X  2  =r  10.4  per  cent. 

4 

32 

Solids  not  fat F  .2  x  2  1=  8.4  per  cent. 

4 

S]xxific  gravity  of  milk  solids 

10.4 

10.4  -  100  X  1.032  -  100  =  T425  per  cent. 

1.032 


CONDKNSKD  MiLK   AND   MiLK   PoWDER  227 


DETECTION  OF  ARTIFICIAL  COLORING^ 

LEACH'S   METHOD 

"Warm  about  150  c.c.  of  milk  in  a  casserole  over  the  flame  and 
add  about  5  c.c.  of  acetic  acid,  after  which  slowly  continue  the 
heating  nearly  to  the  boiling  point  while  stirring.  Gather  the  curd, 
when  possible,  into  one  mass  by  the  stirring  rod,  and  pour  oiT  the 
whey.  If  the  curd  breaks  up  into  small  flakes  separate  from  the 
whey  by  straining  through  a  sieve  or  colander.  Press  the  curd  free 
from  adhering  liquid,  transfer  to  a  small  flask,  and  macerate  for 
several  hours  (preferably  over  night)  in  about  50  c.c.  of  ether,  the 
flask  being  tightly  corked  and  shaken  at  intervals. 

1.     "DETECTION  OF  ANNATTO    (IN  THE   ETHER  EXTRACT) 

"Decant  the  ether  extract  as  obtained  above  into  an  evaporating 
dish,  place  on  the  water  bath,  and  evaporate  the  ether.  Make  the 
fatty  residue  alkaline  with  sodium  hydroxid,  and  pour  upon  a  very 
small  wet  filter  while  still  warm.  After  the  solution  has  passed 
through,  wash  the  fat  from  the  filter  with  a  stream  of  water  and 
dry  the  paper.  If,  after  drying,  the  paper  is  colored  orange,  the 
presence  of  annatto  is  indicated.  Confirm  by  applying  a  drop  of 
stannous  chlorid  solution,  which,  in  presence  of  annatto,  produces 
a  characteristic  pink  on  the  orange-colored  paper. 

2.     "DETECTION  OF  ANILIN  ORANGE  (IN  THE  CURD) 

"The  curd  of  an  uncolored  milk  is  perfectly  white  after  com- 
plete extraction  with  ether,  as  is  also  that  of  a  milk  colored  with 
annatto. 

"If  the  extracted  fat-free  curd  is  distinctly  dyed  an  orange  or 
yellowish  color,  anilin  orange  is  indicated.  To  confirm  the  presence 
of  this  color,  treat  a  lump  of  the  fat-free  curd  in  a  test  tube  with 
a  little  strong  hydrochloric  acid.  If  the  curd  immediately  turns  pink, 
the  presence  of  anilin  orange  is  assured. 


United  States  Departiueut  of  Agriculture,  Bureau  of  Chemistry,  Bulletin  No.  107 


228  Condensed  Milk  and  Milk  Powder 

3.  "DETECTION  OF  CARAMEL  (IN  THE  CURD) 

"If  the  fat- free  curd  is  colored  a  dull  brown,  caramel  is  to  be 
suspected.  Shake  a  lump  of  the  curd,  as  in  (2),  with  strong  hydro- 
chloric acid  in  a  test  tube  and  heat  gently.  In  the  presence  of  cara- 
mel the  acid  solution  will  gradually  turn  a  deep  blue,  as  will  also 
the  white,  fat-free  curd  of  an  uncolored  milk,  while  the  curd  itself 
does  not  change  color.  It  is  only  when  this  blue  coloration  of  the 
acid  occurs  in  connection  with  a  brown  colored  curd,  which  itself 
does  not  change  color,  that  caramel  is  to  be  suspected,  as  dis- 
tinguished from  the  pink  coloration  produced  at  once  under  similar 
conditions  by  anilin  orange." 

4.     "LYTHGOB'iS  TEST  FOR  ANILIN  ORANGE 

"Treat  about  10  c.c.  of  the  milk  with  an  ecjual  volume  of  hydro- 
chloric acid  (sp.  gr.  1.20)  in  a  porcelain  casserole  and  give  the  dish 
a  slight  rotary-motion.  If  an  appreciable  amount  of  anilin  orange 
is  present,  a  pink  color  will  at  once  be  imparted  to  the  curd  particles 
as  they  separate." 

DETECTION   OF  SUCROSE   IN    MILK  TO  WHICH   SUCRATE  OF   LIME' 
(VISCOGEN)    HAS  BEEN   ADDED 

25  C.C.  of  milk  or  cream  are  shaken  in  a  small  Erlenmcyer  flask 
with  10  C.c.  of  a  5  per  cent,  solution  of  uranium  acetate,  allowed  to 
stand  for  five  minutes  and  filtered  through  a  folded  filter.  If  the 
filtrate  is  not  clear,  pour  through  filter  again  until  clear.  To  10  c.c. 
of  the  filtrate  2  c.c.  of  a  cold  saturated  solution  of  ammonium 
molybdate  and  8  c.c.  of  hydrochloric  acid  (one  part  of  25  per  cent, 
acid  to  seven  parts  of  water)  are  added.  The  mixture  is  shaken 
and  placed  in  a  water  bath  at  80  degrees  C.  for  five  minutes.  In  the 
case  of  the  presence  of  sucrose  the  solution  becomes  more  or  less 
blue  according  to  amount  of  sucrose  present.  Upon  standing  in  the 
water  bath  for  a  longer  time  the  blue  color  becomes  deeper.  At  the 
end  of  ten  minutes  it  is  deep  blue,  while  in  the  absence  of  sucrose  at 
the  end  of  five  minutes  the  color  is  faintly  green,  which  deepens, 
but  never  acquires  a  blue  shade.  By  means  of  this  method  as  little 
as  .05  per  cent,  sucrose  can  be  detected. 


Barthel,  Milk  and  Dairy  Products 


Condensed  Milk  and  Milk  Powder  229 

DETECTION   OF  LIME   IN    MILK^ 

Shake  250  c.c.  of  milk  at  15  degrees  C.  with  10  c.c.  of  a  10  per 
cent,  sokition  of  hydrochloric  acid.  Let  stand  at  room  temperature 
for  half  an  hour.  Filter,  returning  the  first  portion  of  filtrate  to  the 
filter.     Cover  filter  to  prevent  evaporation. 

Pour  104  c.c.  of  the  filtrate  (equal  to  100  c.c.  of  milk)  into  a 
200  c.c.  flask,  add  10  c.c.  of  a  10  per  cent,  solution  of  ammonia  and 
fill  the  flask  to  the  mark  with  water  at  15  degrees  C.  Let  stand  for 
thirty  minutes.  Filter  through  folded  filter,  pouring  back  on  the 
filter  the  first  portion  of  the  filtrate.  Test  100  c.c.  of  filtrate  (equiv- 
alent to  50  c.c.  of  milk)  with  10  c.c.  of  5  per  cent,  ammonium 
oxalate  solution  and  proceed  with  the  determination  of  the  lime  in 
the  usual  way,  but  without  warming  the  liquid. 

According  to  Baier  and  Neumann  and  corroborated  by  Luhrig, 
in  normal  milk  the  lime  in  the  serum  is  present  tO'  the  extent  of 
thirteen  to  eighteen  milligrams  per  100  c.c.  In  milk  to  which 
sucrate  of  lime  has  been  added  the  results  are  correspondingly 
higher. 

DETECTION    OF   GELATIN  = 

"Prepare  an  acid  solution  of  mercuric  nitrate  by  dissolving  mer- 
cury in  twice  its  weight  of  nitric  acid  of  1.42  specific  gravity,  and 
diluting  this  solution  to  twenty-five  times  its  bulk  with  water.  To 
lo  c.c.  of  the  milk  or  cream  to  be  examined,  add  an  equal  volume  of 
the  acid  mercuric  nitrate  solution,  shake  the  mixture,  add  20  c.c.  of 
water,  shake  again,  allow  to  stand  five  minutes,  and  filter.  If  much 
gelatin  is  present  the  filtrate  will  be  opalescent  and  cannot  be  ob- 
tained quite  clear.  To  a  portion  of  the  filtrate  contained  in  a  test 
tube,  add  an  equal  volume  of  a  saturated  aqueous  solution  of  picric 
acid.  A  yellow  precipitate  will  be  produced  in  presence  of  any  con- 
.siderable  amount  of  gelatin,  while  smaller  amounts  will  be  indicated 
by  a  cloudiness.  In  the  absence  of  gelatin  the  filtrate  obtained  will 
remain  perfectly  clear." 

DETECTION    OF    PRESERVATIVES 

CARBONATE    OR    BICARBONATE    OF    SODA'     (HILGER'S    METHOD) 
Dilute  50  c.c.  of  milk  with  250  c.c.  of  water.    Heat  and  precipi- 
tate with  a  small  quantity  of  alcohol.     Filter,  evaporate  the  filtrate 


1  Barthel,  Milk  and  Dairy  Products 

2  United  States  Department  of  Agriculture,  Bureau  of  Cliemistry,  Bulletin  107,  1912 


230  Condensed  Milk  and  Milk-Powder 

to  one-half  its  original  volume  and  test  with  litmus  for  an  alkaline 
carbonate. 

FORMALDEHYDE    (HEHNER'S    METHOD) 

Dilute  the  milk  with  an  equal  volume  of  water.  Fill  a  test  tube 
one-half  full.  Add  commercial  sulphuric  acid,  specific  gravity  1.82- 
1.84.  The  acid  should  be  allowed  to  flow  down  the  side  of  the  tube 
so  as  to  avoid  excessive  mixing  of  acid  and  milk.  If  formaldehyde 
is  present  a  violet  ring  forms  at  the  junction  of  milk  and  acid.  By 
this  test  the  presence  of  one  part  of  formaldehyde  in  two  hundred 
thousand  parts  of  milk  can  be  detected.  When  more  than  .05  per 
cent,  formaldehyde  is  present  the  violet  color  does  not  appear. 

The  same  color  reaction  is  obtained  when  the  acid  is  added  to 
the  milk  in  the  Babcock  test. 

Farrington  and  WolP  recommend  the  following  method: 
Measure  5  c.c.  of  milk  in  a  white  porcelain  dish,  add  5  c.c.  of  water, 
and  10  c.c.  of  hydrochloric  acid  containing  a  trace  of  ferric  chloride 
(FeoClg).  Heat  the  mixture.  If  formaldehyde  is  present  a  violet 
color  appears. 

BORIC  ACID  AND  BORATES' 

"Render  decidedly  alkaline  with  lime  water  about  25  grams  of 
the  sample  and  evaporate  to  dryness  on  a  water  bath.  Ignite  the 
residue  to  destroy  organic  matter.  Digest  with  about  15  c.c.  of 
water,  add  hydrochloric  acid,  drop  by  drop,  until  all  is  dissolved, 
and  add  i  c.c.  in  excess.  ^loisten  a  piece  of  delicate  turmeric  paper 
with  the  solution;  if  borax  or  boric  acid  is  present,  the  paper  on 
drying  will  acquire  a  peculiar  red  color,  which  is  changed  by  am- 
monium hydroxid  to  a  dark  blue-green,  but  is  restored  by  acid. 

A  preliminary  test  may  be  made  by  immersing  a  strip  of  tur- 
meric paper  in  about  100  c.c.  of  liquid  foods,  to  which  about  7  c.c. 
of  concentrated  hydrochloric  acid  has  been  added.  Solid  and  pasty 
goods  may  be  heated  with  enough  water  to  make  them  thoroughly 
fluid,  hydrochloric  acid  added  in  about  the  proportion  of  i  to  13, 
and  tested  in  the  same  manner." 

"  BENZOIC  ACID  = 
"Add  5  c.c.  of  dilute  hydrochloric  acid  to  50  c.c.  of  the  milk 
in  a  flask  and  shake  to  curdle.    Then  add  150  c.c.  of  ether,  cork  the 


1  Farrington  «&  Woll,  Testing  Milk  and  its  Products 

=  United  States  Department  of  .Agriculture.  Bureau  of  Gheuiistry,  Bulletin  107,  1912 


Condensed  Milk  and  Milk  Powder  231 

flask  and  shake  well.  Break  up  the  emulsion  which  forms  by  aid 
of  a  centrifuge,  or  if  the  latter  is  not  available  extract  the  curdled 
milk  by  gently  shaking  with  successive  portions  of  ether,  avoiding 
the  formation  of  an  emulsion.  Transfer  the  ether  extract  (evapo- 
rated to  small  volume  if  large  in  bulk)  to  a  separatory  funnel  and 
separate  the  benzoic  acid  from  the  fat  by  shaking  out  with  dilute 
ammonium  hydroxid,  which  takes  out  the  former  as  ammonium 
benzoate.  Evaporate  the  ammoniacal  solution  in  a  dish  over  the 
water  bath  till  all  free  ammonia  has  disappeared,  but  before  dryness 
is  reached,  add  a  few  drops  of  ferric  chlorid  reagent.  The  char- 
acteristic flesh-colored  precipitate  indicates  benzoic  acid.  Care 
should  be  taken  not  to  add  the  ferric  chlorid  until  all  the  ammonia 
has  been  driven  off,  otherwise  a  precipitate  of  ferric  hydrate  is 
formed." 

SALICYLIC    ACID^ 

Acidulate  20  c.c.  of  milk  with  sulphuric  acid  and  shake  with 
ether.  Evaporate  the  ether  solution  and  treat  the  residue  with  al- 
cohol and  a  little  iron-chloride  solution ;  a  deep  violet  color  indi- 
cates the  presence  of  salicylic  acid. 

HYDROGEiN  PEROXIDE" 
(Wilkinson  and  Peters'  Method) 

Add  four  drops  of  an  alcoholic  solution  of  4  per  cent,  benzi- 
dine (paradiamidodephenyl)  and  2  drops  of  acetic  acid  to  10  c.c.  of 
milk.  If  hydrogen  peroxide  is  present  the  milk  assumes  a  blue 
color.  .005  grams  of  hydrogen  peroxide  in  100  c.c.  of  milk  can  be 
detected  by  this  method. 

CHAPTER  XXXII 

BACTERIOLOGICAL   ANALYSIS 

It  is  not  the  purpose  of  this  volume  to  discuss  in  detail  the 
technique  of  bacteriological  analyses  of  the  milk  products  described 
herein.  The  methods  and  technique  of  determining  the  bacterio- 
logical flora,  quantitatively  and  qualitatively,  are  identical  to  those 
used  in  the  bacteriological  study  of  milk  and  other  food  products, 
and  which  are  fully  described  in  manuals  on  bacteriology. 


Farrington  and  Woll,  Testing  Milk  and  Its  Products 
Barthel,  Milk  and  Dairy  Products 


232  Condensed  Milk  and  Milk  Powder 

As  a  guide  to  those  who  are  not  familiar  with  the  peculiarities 
of  bacterial  fermentations  of  condensed  milk,  it  may  suffice  to  state 
that,  in  the  case  of  sweetened  condensed  milk,  the  destructive  biolog- 
ical agents  are  largely  confined  to  yeast,  which  grow  best  in  media 
containing  a^high  per  cent,  of  sucrose. 

In  the  case  of  evaporated  milk  the  direct  cause  of  fermenta- 
tion usually  lies  in  the  presence  in  such  milk  of  very  resistant,  spore- 
bearing  bacteria,  usually  of  the  butyric  acid  type  and  often  belong- 
ing to  the  putrefactive  species.  In  the  majority  of  cases  these  or- 
ganisms demand  anaerobic  cultural  conditions. 


Condensed  Mii,k  and  Milk  Powder 
*Legal  Standards  for  Dairy  Products 


233 


states 

Milk 

Skim 
milk 

Cream 

But- 
ter 

Whole 
milk 
cheese 

Condensed 
milk 

Ice 
cream 
(plain) 

Ice 
cream 
(fruit 

and 
nut) 

Total 
solids 

Solids 
not 
fat 

Fat 

Total 
solids 

Fat 

Fat 

Pat 

Total 
solids 

Fat 

Pat 

Pat 

Alabama    

Arizona    

Arkansas  

California  

Pr.  ct. 
11.5 

Pr.  ct. 
8.5 

Pr.  ct. 

3.0 
3.0 
3.25 

3.5 
3.25 

Z.O 
3.2 
3.0 
3.25 
3.0 
3.25 
3.25 
3.5 
3.25 
3.5 
3.25 
3.0 
3.25 

3.25 
3.25 
3.0 

3^0 

3.0 
3.25 
3.25 
3.0 
3.0 
3.0 
3.2 
3  25 

Pr.  ct. 

8.8 

9.3 
9.25 
9.25 

Pr.  ct. 
X 
N 

Fed 

18.0 

3  16.0 

16.0 

N 

20.0 
18.0 
18.0 

Pr.  ct.  I  Pr.  ct. 
0  State  standar 
0  State  standar 
eral  rulings  ado 
80.0         1 51) 
80.0         1  .50 

Pr.  ct. 

)s 
Is 

pted 
(=) 

Pr.  ct. 

Pr.  ct. 

12 
14 

Pr.  ct. 

11.75 

12., 3 
11.7r> 
11.75 
11.5 
11.2 
11.5 

""12^0' 
11.75 
12.5 

8.5 

9.0 
8.5 
8.5 
8.5 

8.0 
8.5 
8.5 

"'T.l' 
8.5 
8.5 
8.5 

""9"75 

8.75 
8.5 

Delaware 

District  of 
Columbia 

0  State 
83.0 
8215 

standar 

3s 

Florida  

Georgia 

Hawaii  '■  

1  50 
1  50 

••28.0 
28.0 
28.0 
(-) 
(=>) 
28.0 

"72)"" 
28.0 
(2) 

•'7.7 

"7.7 

{-) 

{-) 

127.5 

— (o-)— 
1  26.76 

12 
14 

--- 

Idaho- 

Illinois    

Indiana    

Iowa 

9.3 
9.25 
9.26 

9.26 
8.0 

■"'9"25 
9.3 

18.0 
18.0 
18.0 
16.0 
M8.0 
18.0 
18.0 
18.0 
18.0 
15.0 

8.25 

82.5 

82.5 

9  80.0 

Si. 5 

30 

150 
150 

1  50 
150 

14 
8 
8 
12 
14 
14 

12 

Kansas   

Kentucky 

12 

12 

Maine 

11.75 
12.5 
12.15 
12.5 
1.3.0 

12.0 
11.75 

Maryland    

(-) 

(=) 

4 

Michigan    

12 
12 

14 

14 

14 

M4 

Minnesota  

Mississippi 

Missouri  

Montana 

9. ,25 

""IT 

""9"25 
9.-i5 

26.0 

N 
18.0 
20.0 
18.0 
18.0 
16.0 

N 
18.0 
18.0 
18.0 
15.0 

0  State" 
8.25 
8.25 

14.5 
?tandarf 

lEO 
153 

28.0 

{■') 
-1.1& 

Nebraska 

1'' 

New  Hampshire 

12.0 
11.5 

11.5 
11.75 
11.75 
12.0 
12.0 
12.51 

8.5 
9.0 

V.l' 
9.0 

■"""9^0' 

8.5 
8.5 
8.5 
9.0 
9.25 
8.5 
8.75 

8.5 
8.5 

80.0 



New    Mexico 

0  State 

standarc 

Is 
(») 
26.5 
28.0 

1  25.0 

7.8 

127.5 

Nevada   

North    Carolina 
North    Dakota 

82.5 

1.50 
150 

14 
14 
14 

ii* 

Ohio 

0  80.0 
81.5 

(10) 

1  2-..0 

Oklahoma  

W—V". 

18.0 
20.0 
18.0 

14 
12 

8 

" 

30.0 
32.0 

(") 

(") 

Pennsylvania  .. 
Porto  Rico 

12.0 
12.0 
12.0 

6 

3.0 
2.5 

South  Carolina 
South  Dakota-- 
Tennessee 

3.25 
3.25 
3.25 
3.2 

"""3"25 
3.25 

3.0 
3.25 

9.25 

N 
18.0 

0  State 
80.0 

tandarc 
150 

s 

28.0 

127.5 

14 

12 

Texas  

Utah    

Vermont 

Virginia    

Washington 

12.0 

'3  12.5 

11.75 

12.0 

9.0 

'""9^2.^ 
9.3 

9.0 
9.25 

18.0 

""il'.o' 

18.0 

80.0 
82^5" 

1  .50 

—{2)-- 

n 

""{"-)" 

li 

12 

West  Virginia- 
Wisconsin   _  _  _ 

No  State  standard 
18  0        82  5  1       1 .50 

s 
99.  (\ 

8.0 

(13) 

14 
14 

18.0         82  5  1       1 .50  1      98.0 

12 

1 

1 

1  Percentage  of  fat  based  on  total  solids 

2  Fat.  7.8  per  cent.;  total  solids  plus  fat,  34.3  per  cent. 
»  For  buttermaking,  25  per  cent,  fat 

*  This  standard  for  sweetened  condensed  milk:   "Evaporated  milk,"'  solids,  24  per  cent.;  fat,  7.8 
per  cent. 

s  No  report;  1910  standard  given 

«  By  weight 

■^  Not  more  than  0.2  per  cent,  "filler" 

8  Must  correspond  to  11.5  per  cent,  solids  in  crude  milk 

»  If  artificially  colored 

1"  Must  correspond  to  12  per  cent,  solid  in  crude  milk 

11  23-24  per  cent,  solids,  7.9  per  cent,   fat;  24-25  per  cent,  solids,  7.8  per  cent,   fat;  25-26  per  cent, 
solids,  7.7  per  cent,  fat;  26  per  cent,  solids,  7.6  per  cent,  fat 
1=  In  May  and  .Tune,  solids  12  per  cent. 
13  Fat,  27.5  per  cent,  of  total  solids 

•  United  States  Department  of  Agriculture,  Bureau  of  Animal  Indui^try,  Circular  218,  1913 


Condensed  Milk  and  Milk  Powder 


235 


INDEX 


Absolute    pressure    58 

Absolute   vacuum    58 

Accidents   in   operating   pan,   preven- 
tion   of    65 

Acid  fermentation   171 

Acid   flux   79,  92, 152, 153, 166 

Acid  in  milk  158 

Acid    tests    30 

Actinomycoses  odorifora  162 

Adulterants    177 

detection  of  222 

Age    112, 113, 114, 150, 164 

Agitation    72,  73, 146 

Air    162 

Albumin  125,  148,  204 

Altitude    58,  59,  60,  61 

Altitude  of  various  cities  in  U.  S 60 

Altitude,  relation  to  atmospheric  pres- 
sure     58,  61 

Ammonium    hydroxide    179 

Analyses  of,  evaporated  milk 127,  215 

milk  200 

milk  powder  221 

sweetened  condensed  milk 122,  210 

Anglo-Swiss   Condensed  Milk  Co 12 

Annatto,   detection   of 227 

Anilin   orange,   detection  of 227,  228 

Artificial    coloring    227 

Artificial   fats   136, 163,  178 

Ash 121,  3  26,  167,  202,  212,  220,  221 

Atmospheric    pressure    58 

B 

Babcoek  test 209,  213,  220,  222 

Bacteria  and  other  fungi, 

Actinomycoses  odorifora 162 

Bacillus   dimorphobutyricus   159 

Bacillus    esterificans    159 

Bticillus    mesentericus     162 

Bacillus    putrificus    159 

Bacillus   saccharobutyricus   159 

Bacterium   fluorescens   162 

Bacterium  prodigiosum  162 

Cladosporium   butyri   162 

Oidium    lactis    162 

Penicilium  glaucum  162 

Penicilium  roqueforti  162 

Plectridium    foetidum    159,174.175 

Plectridium  novum  159,174 


Bacteriological   analyses   231 

Barometric    condenser    50 

Barometric    reading    at    different    al- 
titudes      59 

Barrels,  condensed  milk  73, 154 

Basis  of  buying  milk  27 

Beaume    hydrometer    

-.68,  69,  70,  84,  85,  86,  165,  210,  215 

Beet    sugar 41 

Benzoic    acid,    detection    of „... 230 

Bicarbonate  of  soda 179,  182,  229 

Bitter   curd  in  evaporated  milk 

172,  173,  174 

Blow-down  valve,  or  vaccum  breaker..  49 

Body,  or  vapor  belt  47 

Boiling    test    31 

Borden's    Condensed   Milk   Co 12 

Borden,   Gail   10,  11,  12 

Boric  acid  and  borates,  detection  of..230 

Box    shooks    Ill,  138 

Brands    116 

Brown    evaporated   milk 125, 176, 177 


Camjjbell   process   102, 103 

Cane    sugar    40, 150, 155 

amount   of   43, 155, 160 

determination  of 215,  221,  228 

effect   on   color   164 

effect   on   digestibility..43,  130, 131, 132 

effect   on   sugar   sediment 143,148 

effect    on    thickening 44, 149 

incomplete   solution   of   143 

mixing    of 44,  45, 121, 122, 143, 157 

preservative  properties  of  40,  44 

price    of   44, 137 

quality    of    42,155,156,158 

solubility    of    121,122 

solution  of  143 

Caramel,   detection   of 228 

Carbonate  of  soda,  detection  of 229 

Care  of  milk  utensils  29,  159 

Casein 120,  124,  125,  204 

Casinate  of  zinc  79,  153 

Catch-all,  or  milk  trap  53 

Checking  work  of  sealers  108 

Classification    of   condensed   milk   de- 
fects     141, 142 

Coal  137 

Coating  on  jacket   and  coils 120 

Coils  in  vacuum  pan  47 


236 


Condensed  Milk  and  Milk  Powder 


Colostrum,   effect   of   148 

Commereial   glucose   40, 163, 178 

Composition   of, 

concentrated    milk    126 

condensed    buttermilk    105 

evaporated   milk   123 

fat   in   condensed   milk   124 

milk  powder  189 

plain  condensed  bulk  milk 126 

sweetened  condensed  milk  119 

Concentrated   milk   102 

Concentration,    ratio    of 

66,   101,104,147,160 

Condensed   buttermilk   104 

Condensed  milk  factories  16 

drainage   of   20 

economic    arrangement  of  machinery  26 

equipment,   list   of   24,  25.  26 

essentials  of  suitable  location  of....  16 

factory  sanitation  35,  150,  157 

floor  plan  of  factory  21,  22,  23 

milk  supply  16 

sanitary  arrangement  of  machinery 

26,   157 

sewage  disposal  19 

tin   shop   23 

transportation  facilities  18 

water  supply  17,  162 

Condensed   milk   industry   9 

Condensed   skim   milk   136 

Condensed  whey,  primost,  myseost 106 

Condensery  regulations 28,  29 

Condenser    discharge 53,  63,  64 

Condensers   50 

.   Barometric  50 

capacity   of   62 

care  of  52 

surface    50 

wet-vacuum  spray  51 

Condensing  evaporated  milk   83,  170 

Condensing  plain  condensed  bulk  milk.. 101 
Condensing  sweetened  condensed  milk 

45,  64,  65,  66,  150 

Contaminated    machinery    26,  36, 157 

Contaminated    sugar.. ..40,  41,  42,  155,  166 

Contamination  of  milk  in  factory 156 

Contamination  of  milk  on  farm 

27,  28,  150,151,156 

Control  of  quality  of  fresh  milk 28 

Cooling   29,  89,  102 

Cooling   in    sterilizer   96,  166 

Cooling  sweetened  condensed  milk, 

agitation    72,  73,  146 

effect  on  sugar  crystallization.... 72, 145 

equipment  for  72 

method    of    , 72 

temperature    72,  73 

Cost  of  manufacture  136 

Cream  of  tartar  180 


Curdy  evaporated  milk,  caused  by 

acid    flux    in    cans 92,166 

'  concentration   84,  85, 134, 165 

fractional  curdling  97, 166 

fractional  sterilization 97 

homogenizing    88,  166 

quality  of  fresh  milk..27,  28,  81,  82,  165 

sterilizing    heat    ....95,  96, 166 

shaking  97,98,99 

Curdy  plain  condensed  bulk  milk, 

effect  of  qualitj'  of  fresh  milk 

27,  28,  100,164,165 

neutralizing  the  acid  165 

D 

Decomposition   of, 

lactose  155 

sucrose 156 

Defective    cans    172 

Defective  evaporated  milk 164 

Defective  milk  i:)owder  192 

Defective  sweetened  condensed  milk..l41 

Dehydrated  milk  181 

Desiccated    milk    181 

Detection    of   beet   sugar   42 

Difficulties  in  meeting  evaported  milk 

standards    134, 165 

Digestibility    of    condensed    milk 

128,   130,131,132 

Digestion    experiments    128, 129, 130 

Dilution  of  condensed  milk  131 

Distribution   of   factories   in   U.    S 15 

Distribution    of   heat   in   sterilizer 94 

Dome  49 

Drawing  off  condensed  milk  71 

Drips  from  jacket  and  coils  48 

Dried  buttermilk  195,  196 

Dried  whey  195,  196 

Duration    of    sterilizing   process 

95,  166,  169 

Dry   milk    181 

Dry-vacuum    pump    54 

E 

Economic   arrangement   of  machinery  26 
Effect  of  heat  on  ash  of  milk....l26^  127 

Efficiency  of  shakers 99 

Efficiency  of  vacuum  pan  46 

Efficiency   of   vacuum   pump    55 

Enzymes   in    condensed   milk 130 

Equipment    of    condensery 24,  25,  26 

Evaporated  milk 13,  81,  123,  164,  215 

Evaporated  milk  standards   133, 134 

Evaporation,  affected  by 12 

ratio  of  steam   and  water   64 

steam   pressure  in  jacket  and  coils  61 
temperature  of  condenser  discharge 
61,  62,  63 


Condensed  Milk  and  Milk  Powder 


237 


temperature  in  pan  61,62,63 

vacuum  in  pan   61,62,63 

water   in   condenser   61,62,63 

Excessive   chilling   in   pan   144 

Excessive   stirring   of   sweetened   con- 
densed milk  72,  73,  146 

Exports  of  condensed  milk  117, 118 


Homogenizing, 

effect    on    curdiness    88, 166 

effect  on  fat  separation  86,  87,  88, 170 

purpose   86, 170 

principle   87 

How  to  keep  factory  in  sanitary  con- 
dition     26, 36, 150, 151, 157 

Hydrogen   peroxide,   detection   of 231 


Factory  sanitation  26,  35,  36, 150,  151,  157 

Fat  globules,  size  of 124,  168 

Fat  in   condensed  milk 

120,  124,  147,  168,  209,  210,  220,  221 

222 

Feed  for  dairy  cows .....28,  159 

Fermented    evaporated    milk 109,171 

Fermented  sweetened  condensed  milk. .154 

Fermentation    tests    33 

Filling,    in    barrels    73, 154 

in   cans   74,  91 

Filling    machines    75,  90 

Finishing  the  batch,    (see  striking) 

Flux  for  soldering 79,152,153 

Food  value  of  condensed  milk 131 

Food  inspection  decision  No.  131 136 

Forewarmers,    heat   in....37,  38,  39,  40, 156 

Formaldehyde,  detection  of  230 

Fractional  sterilization   97,  166 


I 


Imports    of    condensed    milk 117,118 

Improper    cooling    72,  73,  145 

Incomplete   solution   of   cane  sugar.... 

44,  45,  121,122,143 

Incomplete    sterilization    172 

Incubation  99,  100 

Individual  standards  135 

Insoluble    albumin    125 

Inspection  of  cans  108, 171 

Interest   on    investment 138 

Invention   of   condensed   milk  process     9 
Invertase  156,  158 


Jacket   in  vacuum   pan 


47 


Gaseous    fermentation    in    evaporated 

milk   174,   175 

Gas   generators   80 

Gasoline    137 

Gas  supply  79 

Gebee  seal  76 

Gelatin,   detection   of 229 

Glucose   40,158,163,178 

Grainy   evaporated   milk 126,167 

Gritty    j)lain    condensed!    bulk    milk, 
caused  by, 

crj-stallization  of  milk  sugar 

121,  142,  143,  144,  145,  177 

degree   of  concentration   177 

Gunning  method  202 

H 

Hand    sealing    77 

Health   of   cows   '. : 28 

Heating  the  fresh  milk, 

method  of  38,  39,  40,  169 

purpose  of  37,82,83,100,163 

temperature    38, 100,  156, 163 

Homogenizers    87,  88, 166 


Labeling   109 

Labeling  machines  109 

Labels,    cost    of    137 

quality  of  HO 

rust  spots  and  wrinkles  110 

Labor    138 

Lactase  155 

Lactose,    (see  milk   sugar) 

Leach 's    method,    detection    of    color- 


ig 


.227 


Leaky  cans,  disposition  of 108 

Lime,  detection  of  229 

Loading    the    sterilizer    94 

Low's  volumetric  method 206 

Lumpy     sweetened     condensed     milk, 
caused  by, 

acid  flux  in  tin  cans 79, 152, 153 

easinate  of  zinc  79,  153 

contaminated    barrels    73, 154 

milk  from  fresh  cows  

27,  28,  29, 151, 152 

poor  quality  of  fresh  milk....27,  28,  150 

unclean  factory  conditions  

26,  35,  36.  150,  151 

unclean  tin  cans  154 

white  and  yellow  buttons  154 


238 


Condensed  Milk  and  Milk  Powder 


M 

McDonald   seal   :— 76 

Market  prices  116 

Markets  of  condensed  milk  116 

Marking  the  cases  Ill 

Milk,   quality   of   27,28,29,100,150,151, 
152,  155,  158,  159,  164,  165,  179 

control   of   quality   28 

Milk   draw   pipe   48 

Milkers    and    milking    29 

Milk    of    lime 104, 105, 165, 179 

Milk   powder    181 

analysis  of  191,  221 

Campbell   process   186,187 

composition  191 

Eckenburg  process   184 

history   and   development  of   indus- 
try    181 

Just-Hatmaker   process   184 

markets  194 

Merrell-Gere  process 187,  188,  191 

miscibility    193 

packing  for  market  191 

Passburg   process    184, 185 

quality  of  fresh  milk  183 

rancidity   193,   194 

solubility  191,  192 

water    content   192 

Wimmer  process  183 

Milk  strainers  29, 159 

Milk  sugar,  lactose 

caramelizing   action   121,125 

color  125,  164,  177 

crystallization  121,  143,  144,  145,  146, 
177 

decomposition    155 

determination  204,  213,  220,  221 

solubility  121,   142 

Milk  tests  for  purity, 

acid    tests    30 

boiling   test    31 

sediment    test    32 

sense  of  smell  and  taste  29 

temperature  test  30 

Milk  trap 53 

N 

Neutralizers  104,  179 

Neutralizing    165 

New   York   Condensed   Milk  Co, 12 

Nitrogen  202 

Nutritive  ratio  in  sweetened  condens.- 
ed  milk  131 

0 

Oleic    acid    162 

Old  cans  on  the  farm  159 


Operation  of,  homogenizer 88 

vacuum  pan  64,  65 

vacuum   pumps    55 

Output  of  condensed  milk  in  U.  S 14 

Oxidation    of    olein    162 


Packing    HI 

Packing  for  export  HI 

Peroxide  of  hydrogen,  detection  of.. ..231 
Plain   condensed   bulk   milk....ll,  100, 164 

Polluted    water    17,  162 

Poor  quality  of,  fresh  milk 27,  28,  150 

sugar   42, 155, 156, 158 

Practical  methods  of  systematic  ex- 
amination of  condensed  milk  for 
marketable  properties.... 197,  198,  199 

Premiums,   cost  of  138 

Preservatives,    detection    of    229 

Pressure,   atmospheric   58,  61 

in   homogenizer   88, 166 

steam 61,  64,  66,  150 

Primost  106 

Proteids  120,  124,  125,  202,  213,  220,  221 
Putrid     sweetened     condensed     milk, 
38,  39,  40,  113,  163 


Qualifications   of   processor 96,    166 

Quality  of,  fresh  milk,  27,  28,  81,  82,  100 
150,  164,  165,  183 

sugar  42,  155,  156,  158 

Quevenne   lactometer   201 

R 

Eancid  sweetened  condensed  milk,  af- 
fected by, 

air,  light,   heat   162 

artificial  fats  136,  163,  178 

bacteria,   yeast,  molds 162 

glucose  163,   178 

oleic  acid   162 

polluted  water  17,162 

tropical  climates  163 

Eapidity  of  cooling  in  sterilizer.. ..96, 166 
Eelation  of  steam  pressure  to  boiling 

point    56,  57 

Roese-Gottlieb  method 213,  221,  222 

Rust  spots  on  labels  110 


Salicylic   acid,   detection   of 231 

Sampling   of   batch    71 

Sampling   devices   71 

Sandy  sweetened  condensed  milk 142 

caused  by, 
cane  sugar  content  143, 148 


Condensed  Milk  and  Mii,k  Powder 


239 


chilling  in  pan   144 

cooling,    improper 72,  73, 145 

incomplete   solution   of   cane   sugar 

44,  45,  121,  122,  143 

stirring,  excessive  72,  73,  146 

superheating    in    pan 66,  144 

warming    up    too     cool     condensed 

milk  146 

Sanitary  can   74,  76 

Sanitary  purity  of  condensed  milk.... 127 

Sealing   cans   76,  92, 166 

Sealing  machines   77,  92 

Sediment   test    : 32 

Selling  expense  138 

Separation  of  fat  in  evaporated  milk, 
affected  by, 

concentration   169 

fat  globules,  size  of  124,  168 

homogenizing  86,  87,  88,  170 

locality    168 

period  of  lactation  168 

season    168 

sterilizing  process  93,  95,  169 

superheating  in  pan  83,170 

turning  cans  in  storage  170 

Settled  sweetened  condensed   milk 146 

affected  by, 

cane  sugar  content  44,  148 

density  of  condensed  milk  147 

fat    content    147 

turning  cans  in  storage  148 

Sewage   disposal   19 

Shakers  98,  99 

Shaking  97,  98,  99 

Sight  glass  49 

Skimming,  detection  of  222,  224,  225,  226 
Solder,  78;  cost  of,  137;  seals  with....  76 
Solids  in,  evaporated  milk....l23,  216,  217 
218,  219,  220 

milk 201 

milk  powder  221 

sweetened    condensed   milk 

119,  212,  215 

Solids  not  fat 224,  225,  226 

Specific  gravity  122,  126, 'l47,  200,  201, 
210,  211,  212,  215,  216,  224,  225,  226 

Stables  29,  159 

Standardizing  vat  85 

Standards    of,    condensed    skim    milk 

136,   233 

evaporated  milk  133,  134,  233 

sweetened  condensed  milk 132,  233 

individual   , 135 

by    states    233 

Starch  in  condensed  milk  180 

Starting  the  pan   64 

Steam  necessary  for  evaporation 64 

Sterilizers  93 


Sterilizing,  distribution  of  heat 94 

duration  95,  166,  169 

temperature 95,   96,   166 

Storage,  advisability  of 114,  150,  176 

duration  113,  150,  164 

purpose   112 

temperature 113,  160,  161,  164,  175 

turning  cans  in  148,  170 

Straining  29,  159 

Strainers   71,   144 

Striking  or  finishing,  evaported  milk  83 

plain  condensed  bulk  milk 101 

sweetened  condensed  milk 66,  67,  68 

Sucrate  of  lime,  detection  of 228,  229 

Sucrose,    (see   cane   sugar) 

Sugar   chute   45,   157 

Superheating    IQl 

Swelled  cans  due  to,  chemical  action  176 

low  temperature  113,  175 

Sweetened  condensed  milk,  11,  13,  37,  107 
119,  131,  139,  141,  164,  177,  210     . 
Sweetened   condensed   milk   for   baby 
food  131 


Temperature    of   condenser    discharge  64 
Tests  and  analyses  of  milk,  condensed 

milk,  and  milk  powder  197 

Tests   for   fat    34 

Thermometer  in  vacuum  pan 49 

Tin  cans,  cost  of  137 

Tin    shop    26 

Total  cost  per  case  139 

Transportation,  115;  cost  of,  138,  fa- 
cilities for   ; 18 


A'acuo,  science  and  practice  of  evap- 
oration in,  55,  56,  57,  58,  59,  60,  61, 
62,  63,  64 

Vacuum  pan  45,  46,  47,  48,  49 

Vacuum  pump  54,  55 

Veuthole   cans   91 

Venthole  fillers   91 

w 

Warming  up  too  cold  sweetened  con- 
densed milk  146 

Water,  detection  of  in  milk  224,  225,  226 

in  condenser  61,  62,  63 

in  evaporated  milk  123 

in  sweetened  condensed  milk  119 

supply  17,  162 

Westphal  balance  201 

Wet-vacuum  spray  condenser  51 


Yeast 


.156,   159 


240  Condensed  Milk  and  Milk  Powder 


INDEX  TO  ADVERTISERS 


Page 

American  Can  Co 241 

Barber  Creamery  Supply  Co.,  A.  H 242 

Bausch  and  Lomb  Optical  Co 242 

Bessire  &  Co 243 

Burt  Machine  Co 244 

Dairy  Machinery  and  Construction  Co 247 

De  Laval  Separator  Co 245 

Dickerson,   F.   G 246 

Eimer  and  Amend  247 

Ford  &  Co.,  J.  B 248 

Greiner,  Emil    249 

Grelck,  Wm 249 

Harris  &  Co.,  Arthur  250 

Higbee  Co.,  F.  K 249 

Howe  Scale  Co 256 

Leitz,  Ernst  251 

Nafls,  Louis  F 251 

Sargent  &  Co.,  E.  H 256 

Schaefer  Manufacturing  Co 252 

Spencer  Lens  Co 253 

Sprague  Canning  Machinery  Co 254 

Stevenson  Cold  Storage  Door  Co 255 

Stier  Manufacturing  and  Engineering  Co.,  Herman.  . .  256 

Sturges  &  Burn  Manufacturing  Co 260 

Tagliabue  Manufacturing  Co.,  C.  J 257 

Taylor  Instrument  Co 258 

The  Engineering  Co ' 259 

The  Preservaline  Manufacturing  Co 262 

The  Torsion  Balance  Co 260 

Union  Fibre  Co 262 

Wagner  Glass  Works  261 


Condensed  Milk  and  Miek  Powder  241 

MILK  CANS 

REGULAR 
and  SANITARY  Style 

made  in 

sizes  to  suit  all  trade 

requirements 

Uniform  Quality  Prompt  Service 


Shipments  made  from  nearest  factory 

saving  delays  and  freight 

charges. 


American  Can  Co, 

NEW  YORK 

Chicago  San  Francisco 

Montreal  Portland,  Ore. 


WITH    OFFICES    IN    ALL    LARGE   CITIES 


24: 


Condensed  Milk  and  Milk  Powder 


Be  sure  to  get  the  General   Catalogue  of  the  SIITIDIGX   IntGmdl 

A,  H.  Barber  Creamery  Supply  Go,   Tube  Heaters  and  coolers 


CHICAGO,    ILLINOIS 


And    other    tilings 
t  ere  Sit   you. 

The  Internal  Tube  System 
does  iuvay  with  the  danger 
of  eontiiminatioD  from  out- 
side sources. 

The  Internal  Tube  System 
saves  loss  from  evaporation 
as  the  milk  during  both  the 
heating  and  cooling  processes 
is  not  subject  to  atmospheric 
conditions. 

The  Internal  Tube  System 
gives  the  greatest  efficiency 
in  heating  and  cooling  as  tlie 
.sections  can  be  connected  up 
on  tlie  regenerative  principle. 

The  Internal  Tube  System 
is  sanitary  to  the  last  degree 
as  every  inch  can  be  thor- 
oughly brushed  and  then 
sterilized  with  live  steam. 

The  Internal  a\ibe  System 
requires  less  floor  space  per 
thousand  pounds  of  milk 
than  any  other  system  yet 
devised. 

The  Internal  Tube  System 
will  bear  the  closest  investi- 
gation if  you  are  building  a 
new  or  remodeling  an  old 
plant. 


Bausch  &  Lomb 
Microscopes 

are  standards  of  optical  and 
mechanical  efficiency* 


Model  FF-8 
Price  $65.00 


rr-8  is  one  of  several  models  especially  designed 
for  hacterloloKical  work.  It  has  all  necessary  ad- 
justments, two  iris  diapliragmis  and  an  optical 
equipment  of  three  objectives,  including  an  oil  im- 
mersion, two  eyepieces  and  an  Abbe  Condenser  in 
quick  acting  screw  substage. 

The  number  of  magniflcations  ol>tainable 
ranges  from  50  to  1260.  Send  for  catalog  describ- 
ing this  and  other  models. 


Bausch  ^  Ipmb  Optical  (g. 

NEW     YORK  WASHINGTON  CHICAGO  SAN    FRANCISCO 

LONDON      riOCHESTEn,N.Y.      fRANKFOar 


Condensed  Milk  and  Milk  Powder 


243 


RAPID  AND  UNIFORM  COOLING 
OF  CONDENSED  MILK 


At  a  large  saving  of  time,  a  very  large  saving  of  expense, 
ENORMOUS  saving  of  labor  by  the  use  of  the 


and  an 


CELEBRATED  "JENSEN"  COIL  SYSTEM 

Circulating  well  water,  hydrant  w^ater,  ice  water  or  brine 
Automatically.  N'O  pumps,  no  trouble,  no  lifting  of  cans  in 
and  out  of  tanks.    Saves  room  as  well. 

INVESTIGATE 


DAIRY  AND  CREAMERY  SUPPLIES 


244 


Condensed  Milk  and  Milk  Powder 


This  Machine  Plays  an  Im- 


portant Part  in  Milk  Canning 

It  labels  as  many  cans  a  day  as  you  require. 
Orders  are  filled  promptly  and  storage  facilities 
never  overtaxed. 


r 


THE  BURT  LABELING  MACHINE 


>i 


Is  used  in  the  small  as  well  as  the  largest  plants  because  there  is 
no  other  way  to  label  cans  so  fast,  neat  and  cheap. 

It  applies  the  label  with  a  hot  moisture-proof  cement  which 
sets  instantly,  thus  preventing  the  label  from  slipping  while  being 
wrapped  around  the  can  and  ensuring  it  always  being  applied  tight 
and  matched  evenly  at  lap.  No  paste  is  put  on  the  can,  so  there's 
no  possibility  of  the  label  discoloring — it  always  looks  as  though 
just    from    the    printer — that    increases   the   sales   value    of   goods. 

Let  us  tell  you  more  about  the  Burt  Labeler — what  it  does  and 
why  you   should    not   be   without   it.     Just   state   size  of  cans   used. 


BURT  MACHINE   COMPANY 

Labeling,  Wrapping   and    Lacquering    Machines 
BALTIMORE,    MD. 


CoNDENSKD  Milk  and  Milk  Powder 


245 


THIS  IS  THE 

MACHINE 

which  is  bein^  installed  in  the  most 
modern  and  up-to-date  milk  plants 
the  country  over 

Makes  milk  more  marketable  be- 
cause it  removes  from  the  milk  con- 
taminations such  as  broken-down  tis- 
sue and  other  undesirable  milk  condi- 
tions which  for  the  most  part  have 
their  origin  in  the  cow's  udder  before  the  milk  is  drawn 
into  the  pail. 

This  is  the  result  you  can  achieve  with  a  DE  LAVAL 
MILK  CLARIFIER,  a  machine  which  is  destined  to  play 
as  important  a  part  in  the  whole  milk  industry  as  the 
cream  separator  has  in  the  production  of  more  and  better 
cream. 

These  machines  are  rapidly  being  installed  by  the 
largest  and  most  progressive  milk  concerns  in  the  country 
and  an  investigation  will  surely  convince  you  that  you  can 
accomplish  immeasurably  better  results  with  a  De  Laval 
Milk  Clariiier  than  with  any  other  so-called  method  of 
straining  and  filtration,  and  with  less  labor  and  expense. 

Machines  can  be  furnished  in  various  capacities  from 
12,000  to  100  pounds  per  hour  in  either  turbine,  belt- 
driven  or  hand  driven  styles. 

The  power  required  for  driving  the  largest  capacity 
machine  is  only  %  of  one  horse  power. 

Immediate  installations  can  be  made.  Catalog  and 
other  information  mailed  upon  request. 

THE  DE  LAVAL  SEPARATOR  COMPANY, 

New  York  Chicago  San  Francisco  Seattle 


246 


Condensed  Milk  and  Milk  Powder 


USE  THE  DICKERSON  VENT  FILLER 
It  affords  the  BEST  and  CHEAPEST  PACKAGE 

This  machine  receives  either  soldered  or  sanitary  cans,  and  the  milk,  by  gravity. 
It  fills  rapidly,   accurately,  reliably.     It  neatly  and  securely  seals  at  minimum  cost. 

It  is  simple,  compact,  entirely  automatic,  readily  cleansed  and  sterilized,  very 
dependable  and  will  last  a  life  time. 


BABY  SIZE 

It  enables  the  use  of  cans  that  are  cheaper,  more  portable  and  cleaner.  (The 
smaller  the  hole  the  less  the  dirt.) 

It  simplifies,  systematizes  and  cheapens  all  your  can  handling  and  milk  fillini; 
operations.  It  eliminates  undesirable  labor.  It  avoids  waste  of  solder,  cans  and 
milk.     You  can  have  your  sanitary  cans  made  with   both  ends  on. 

The  baby  filler  fills  baby  cans;  the  tall  filler  tall  cans  and  the  combination 
machine  takes  families  and  tails. 

The  machines  quickly  pay  for  themselves  by  their  own  economy.  You  get  all  the 
sanitary  and  selling  advantages  gratis. 

They  pack  a  better  seller  at  from  4c  to  8c   less  per  case. 

"IM.VKE    rS    PROVE    IT" 

F.    G.    DICKERSON 

541-557  W.  Washington   Blvd.,   Chicago 

268    Market    St.,    San    Francisco.  308    Chestnut    St.,    Philadelphia 


Condensed  Miek  and  Milk  Powder 


247 


TO  THE  MANUFACTURERS 
OF  EVAPORATED  MILK 

We  take  pleasure  in  recommend- 
ing to  you  the  Progress  Homogen> 
Izer  for  treatment  of  your  evaporat- 
ed milk.  We  have  more  Progress 
Homogenizers  in  Condensing  Fac- 
tories than  all  other  manufacturers 
of  Homogenizers  in  Europe  and 
America  put  together.  In  fact,  the 
Progress  Homogenizer  has  proved 
to  be  the  only  machine  that  would 
be  reliable  every  day,  and  have 
enough  capacity  to  be  of  benefit  to 
the  Manufacturer  of  Evaporated 
Milk. 

They  are  used   in  the  leading  factories  for  evaporated  milk  in  this 
country.     Write  us  for  catalog  and  special  information. 

DAIRY  MACHINERY  &  CONSTRUCTION  CO.,  INC. 

DERBY,    CONN. 


FBEAS    ELECTRIC    INCIBATOR 

Accurate  to  a  fraction 

of  a  degree. 

Used   in   Many   of   the  Largest 

Dairy   Laboratories. 


We    Carry    Large    Stocks    of 

LABORATORY 
GLASSWARE 
and  APPARATUS 

of  the  most  dependable  quality. 

HYDROMETERS 
LACTOMETERS 
MILK    CENTRIFUGES 
FERMENTATION    TUBES 
MILK  TESTING  APPARATUS 
MICROSCOPES,    ETC. 

Large   illustrated  Catalog  sent  on  request 


Eimer  &  Amend 


Established  1851 


NEW  YORK  and  PITTSBURG 


248 


CoNDKNSKD  Milk  and  Milk  Powder 


The  Choice  of  Experts 

Never  for  a  moment  does  the  man.  who  thoroughly  understands 
the  making  of  high  quality  butter  forget  that  cleanliness  is  one  of 
the  first  considerations. 

And  that  Is  the  reason  Dairy  Experts  and  Authorities  are 
unanimous  in  their  choice  of 


as'  their  cleaning  agent  for  keeping  factory  utensils  and  containers 
in  the  proper  sanitary  condition. 

Do  you  wonder  why  these  men  specify  Wyandotte  Dairyman's 
Cleaner  and  Cleanser  and  what  there  is  to  Wyandotte  Dairyman's 
Cleaner  and  Cleanser  that  makes  it  their  choice? 

Just  as  you  or  they  would  choose  milk  or  cream  of  the  highest 
quality  for  making  the  best  butter  so  they  for  similar  reasons 
choose  Wyandotte  Dairyman's  Cleaner  and  Cleanser  for  cleaning. 
They  know  it  does  more  cleaning  by  far  than  common  cleaning 
agents.  It  not  only  cleans  better  but  it  drives  away  odors,  stale- 
ness  and  impurities  which  other  cleaners  have  no  power  to  remove. 
And  they  also  know  it  can  do  no  harm  to  the  milk  or  utensils  as 
it  is  free  from  greases,  fats,  caustic,  lye  or  anything  of  a  liariiiful 
nature.  Its  purity  is  as  important  to  them  as  its  sanitary  cleans- 
ing qualities. 


Indian  in  Circle 


In  Every  Package 


Eighty-five  per  cent  of  the  buttermakers 
in  the  United  States  and  Canada  use  Wyan- 
dotte Dairyman's  Cleaner  and  Cleanser,  but 
should  you  be  one  of  the  few  who  are  not 
and  do  not  know  what  this  remarkable 
cleaner  can  do  for  cleaning  dairy  utensils 
merely  write  your  supply  man  for  a  keg  or 
barrel  and  give  it  a  trial.  It  proves  all 
claims  quickly. 


The  J.  B.  FORD  COMPANY,  SOLE  MFRS., 

WYANDOTTE,   MICH.,   U.  S.  A. 
This  Gleaner  has  been  awarded  the  highest  prize  whereTer  exhibited 


Condensed  Milk  and  Milk  Powder  249 

]        The  Emil  Greiner  Co. 

Fulton  and  Cliff  Sts.,  New  York  City 
Established    1880  Incorporated    1905 

Manufacturers  of  Apparatus  for  the 
Testing  of  Milk  and  its  Products 

Hydrometers  and  Thermometers 
for  Milk  Condensing  Plants 

Special  Apparatus  to  Order 
Rohrig  Tube  BABCOCK  TEST   GLASSWARE 


WILLIAM  GRELCK 
Consulting  Dairy  Engineer 

ELGIN,    ILL. 

(Member  American   Chemical    Society) 

Wm.  Grelck  is  prepared  to  advise  on  all  matters  relating  to  the  Milk  Indus- 
try, as  to  Correction  of  Defeets^Formulas  of  Condensing  and  Drying  Milk- 
Malted  Milk  and  Infant  Foods— Plant  and  Machinery— Fuel  Economy- Homo- 
genizing. 


Fred  K.  Higbie  Company 

MANUFACTURERS  AND  JOBBERS 

Creamery  and  Milk  Dealers  Machinery 
and  Supplies 


Send   for   Catalog   of   Refrigerating    Machinery,   Creamery   and    Milk 
Dealers   Equipment  and  Supplies 


FRED  K.  HIGBIE  COMPANY 

E.  C.   PRICE,   Pres.  G.  GREENLEAF,  Sec'y. 

1822   S.   CLARK    ST.,   CHICAGO,    ILL. 


C()M)i:xsi;d  Milk  and  Milk  Powdi-.r 


Arthur  Harris  &  Go. 

Established    1884 

212-218  Curtis  St. 
CHICAGO,  ILL. 


Pioneer   Constructors   of 

MACHINERY  FOR  THE 
MANUFACTURE  OF 

PLAIN,    SUGARED,     EVAPORATED    AND 

MALTED  MILK 

vacuum  pans  sterilizers 

forewarmers  shakers 

vacuum  pumps  labeling  machines 

CAN  COOLERS  RUBBER  PACKED  COCKS 

PIPE  COOLERS  SAMPLERS 

RECEIVING  TANKS  SUPERHEATERS 

STORAGE  TANKS  COOLING  COILS 

FILLING  MACHINES  WEIGH  SCALE  TANKS 

SANITARY  PIPE  AND  FITTINGS 
SOLDERING   COPPERS 
PEEPHOLE  GLASSES 

WRITE    US    REGARDING    YOUR    NEEDS 


Condensed  Milk  and  Milk  Powder 


J5I 


NAFIS 
GLASSWARE 


is  the  kind  used  and  recommended  by  the  larg- 
est creameries,  condensing  plants,  ice  cream 
factories  and  agricultural  colleges  in  the  world. 
Its  uniform  and  superior  quality  combined  with 
the  highest  degree  of  accuracy  always  pro- 
duces the  correct  results.  May  I  send  you  a 
catalogue? 


Branch   Factory 

Wilson,  Nafis  &  Co.,  Ltd. 

Brisbane.  Australia 


Lonis  F.  Nafis 

541  WashinHton  Blvd. 
CHICAGO 


THREE-QUARTERS  OF 
YOUR  MILK  TROUBLES 

...ARE... 

BACTERIOLOGICAL 


LEITZ  MICROSCOPES  ARE 
STANDARD 


Ask  the  U.  S.  Dept.  of  Agricul- 
ture, U.  S.   Pure  Food  Labora- 
tories or  any  Univ^ersit}'  in  the 
world 


Write  for  Literature  "R' 


30  East 
18th  St. 


NEW 
YORK 


2=,2  Condensed  Milk  and  Milk  Powder 

Schaefer  Mfg.  Co. 

Manufacturing   Machinists 

We  manufacture  all   iron  machinery  used   in  processing  evapo- 
rated and  sweetened  condensed   milk. 

STERILIZERS  2  Sizes 

SHAKERS 12  Sizes 

CAN  COOLERS 12  Sizes 

TEST  STERILIZERS. .  .     1  Size 

FLOOR  PLATES 4  Styles 

STEEL  TRAYS 

FILLERS  3  Sizes 


Our  Shaker. 


OUR    SPECIALITY 


Making  Special  Machinery  to  Meet  Your 
Special  Requirements 

SCHAEFER  MFG.  CO. 


BERLIN 


FRANK    D.    CHAPMAN,    Mgr. 

WISCONSIN. 


Condensed  Milk  and  Milk  Powder 


253 


SPENCER 
MICROSCOPE  No.  20H. 

The    Ideal    for      Bactereological     and 
Research  Work. 

ADVANTAGES: 
Side      fine       adjustment — 21/2       times 
finer   than    any    prism      or      lever   fine 
adjustment. 

Drop-swing    Condenser    Mounting. 
Black    lacquered    body    tube,    avoiding 
reflections  of  light. 

Low    compact    construction    affording 
maximum   ease  and  comfort  in   use. 

Large      stage      with      long      arm — un- 
usual   capacity. 
Spencer  Standard  superior  optick. 


Spencer  Microscope  No.  20  H 


SPENCER   MICROSCOPES 

ARE   BUILT  FROM   THE 

Laboratory  Worker's  Standpoint 

There  are  incorporated  in  them  many  features  of 
practical  usability,  features  which  make  for  convenience 
and  comfort  in  use  as  well  as  efficiency  and  durability 
which  others  do  not  have. 


SPENCER  MICROSCOPES 

EXCELL    IN 

I.     Optical  Superiority. 
II.     Mechanical   Perfection. 
III.     Embodiment  of  Improvements  Which   Mark  Them  as  Best 
Adapted  to  Their  Purpose. 


We  are  the  only  American  manufacturers  of  microscopes  making  Apochro- 
matlc  objectives.  Ten  years'  experience  In  building  side-line  ad.justments. 

Bactereological  Apparatus  of  All  Kinds  supplied. 
Get  Our  Quotations. 


Spencer  Lens  Company 

BUFFALO.    N.   Y. 


J54  Condensed  Milk  and  Milk  Powder 


SPRAGUE 

CANNING  MACHINERY  CO. 

MANUFACTURERS    OF 

APPARATUS  AND  MACHINES 
EMPLOYED  IN 

MILK 
CONDENSING 

AND 

CANNING 


ESTIMATES  FURNISHED 
ON  COMPLETE  PLANS 


FACTORY:  SALES  OFFICE: 

HOOPESTON,  CHICAGO, 

ILL.  ILL. 


Condensed  Milk  and  Milk  Powder 


255 


DOORS 


Doors  are  just  a  big  valve  and  are  a  weak  point  in  all  Cold  Storage.  Their 
insulation  is  important,  so  is  their  tightness,  but  their  quickness  is  vastly 
more  so,    because   it   affords   the   workman   less   excuse   for   leavmg   them   open. 

The  Stevenson  Doors  have  been 
developed  with  these  features 
constantly  in  mind.  The  Door- 
frame is  adjustable  to  conform  al- 
ways to  the  Door  thus  insuring 
perfect  fit  and  freedom,  without 
expense  or  refitting.  The  thick 
portion  of  the  Door  fits  loosely  in 
the  frame  and  thus  avoids  bind- 
ing. 

The  overlapping  margin  of  the 
Door  is  held  tightly  to  its  seat 
against  the  face  of  the  Door- 
frame by  powerful  elastic  hinges 
having  the  largest  bearings  made 
for  Doors  of  such  weight.  Its 
Self-Actlng  Roller  Fastener  has 
enormous  strength,  is  arranged 
for  padlock — no  slackening  as  it 
latches — the  soft  hemp  gasket  in 
the  joint  is  always  in  sight.  A 
mere  touch  frees  and  opens  it 
from  either  side. 

Stevenson  Doors  swing  entirely 
out  of  the  passageway,  when 
opened,  the  Doorway  may  hence 
be  6  inches  narrower,  an  impor- 
tant economy  in  refrigeration.  The 
jambs  of  the  Doorframes  are 
straight,  clean,  sanitary.  No  frail 
rebate  strips  in  the  Doorway. 
.  The  opening  in  wall  as  con- 
structed in  this  year  1913,  should  be 
3%  inches  wider  and  4  V2  inches 
higher  than  the  clear  size  of  our 
Doorway.  Follow  construction 
numbered  1  and  2. 

For  Overhead  Track  Doors  this 
rough  opening  should  extend  13% 
inches  above  lower  edge  of  track 
bar.  Doorframes  are  secured  with 
lag  screws  %x4  inches,  inserted 
through   front   casing  at   A. 

Fig.  B.  shows  wooden  bevelled 
threshold  1%  inches  thick.  Con- 
nects lower  ends  of  Doorframe, 
forms  a  part  of  it  and  is  let  down 
into  the  floor.  Xo  feather  edge, 
no  jolt,  no  splinters.  For  ware- 
houses.    Accommodates   trucks.  < 

Fig  C  Concrete  Floors.  Shows  lower  ends  of  Doorframe  extending  down 
into  the  floor  3",  and  connected  by  angle  irons  extending  across  the  Doorway 
from  one  side   to  the  other  below  the  surface.  _ 

Fig.  S.  shows  Doorframe  with  full  standard  sill  and  head,  used  on  all  sizes 
of  Doorframes.     Suited  only  to  walking   through.  ^.«    ,      ,        ,       .    .^^^.t 

Special  Freezer  Doors  for  Icy  Doorways,  on  a  modified  plan  for  intermit- 
tent or  continuous  freezers,  as  well  as  for  general  purposes.  Perfectly  tight 
and  perfectly  free,  regardless  of  temperature,  moisture  or  accumulation  of 
ice  in  any  degree.  „         ^  r.,    j 

Revolving  Ice  Cream  Doors   (Iron).     Do  not  swell  and  bind. 
Combined  Self-Closing  Ice  Door  and  Chute  of  three  styles.     Ice  Counters. 

Stevenson   Cold   Storage  Door   Co. 

CHESTER,    PENNSYI.VANIA 


Installation  Diagrams. 

STOCK    SIZES. 

Stevenson's  Standard  Cold  Storage 
Doors. 

Size  of 
Wall  Opening 
to  receive  our 
Door  Frames 
2-6%  X  2-  4% 
2-3%  x  4-  4% 
2-3%  X  5-  4% 
2-3%  X  5-10% 
2-3%  X  6-  4% 
2-9%  X  6-  4% 
3-3%  x6-  4% 
3-9%  x6-  4% 
4-3%  x6-  4% 
3-3%  x6-10% 
3-9%  x6-10% 
4-3%  x6-10% 


Size  of 
Doorway 
in  Clear 
2-3  X  2-0 
2-0  X  4-0 
2-0  X  5-0 
2-0  X  5-6 
2-0  X  6-0 
2-6  X  6-0 
3-0  X  6-0 
3-6  x6-0 
4-0  X  6-0 
3-0  X  6-6 
3-6  X  6-6 
4-0  X  6-6 


Estimated 
Weight, 
crated 
100 
140 
170 
185 
200 
250 


400 


440 


256 


Condensed  Milk  and  Milk  Powder 


FULL  JEWELED  RUST  PROOF  No.  60  CREAM  TESTING  SCALE 

For  Use  in  Connection  wilh  the  Babcock  Tests 

This  Scale  is  especially  deslKned  for  very 
accunite  welching  of  cream.  It  is  made 
rust-proof,  all  bearings  being  of  agate  and 
the  weighing  plates  of  porcelain.  It  ha.s  a 
wide  bar  in  front  to  balance  the  bottle,  and 
Is  provitled  with  the  necessary  weight. 
Base  of  scale  is  lOJc  in.  long;  the  porcelain 
plates  are  three  iu.  square. 

All  bearings  are  agate,  plates  are  porce- 
lain.   Base  and  under  connections  are  gal- 
vanized, making  a  rust-proof  scale. 
Also  made  in  larger  sizes  to  weigh  6  and   12  bottles.     We  manufacture  scales  for  all 


kinds  of  factory  purposes.     Write  us  for  prices. 

The  Howe  Scale  Co.  of  III. 


1315:WABASH.   CHICAGO 


SARGENT'S  ELECTRIC  DRYING  OVEN 


(PATENTED- 


May  be  set  for  any  temperature 
from  70°  C.  to  150'  C.  and  ivill 
maintain  that  temperature  in- 
definitely. Almost  a  necessity 
in  Milk  Product  Laboratories 
where  the  maintenance  of  the 
lowest  usable  temiierature  is  im- 
perative. 

Price  complete  with  six-foot 
cord,  plug  and  thermometer, 
$25.00.  Woimd  for  110  or  220 
volt  current. 


Complete   catalopues  furnis?ied 
uiwn  application. 


E.  H.  SARGENT  &  CO. 

Manufacturers,   Importers,   Dealers  in  Chemicals  and  Chemical  Apparatus 
of  High   Grade  only. 

125-127  West  Lake  Street         -         Chicago 


HERMAN  STIER 

Manutacturing  and  Engineering  Go, 

CHICAGO,  ILL. 

Designers  and  builders  cf  complete  Plants  and 
Specialities  for  the  manufacture  of  Industrial 
Milk  Products,  Butter,  Condensed  Milk,  Sugar, 
Cheese,  Flour,  Buttermilk,  Casein,  Albumen, 
Salts,  Acids,  etc. 

High    class    design    and    work    only 


Condensed  Milk  and  Milk  Powder 


257 


"TEMPERATURE  CONTROL 
IS  THE  MOST  IMPORTANT 
FACTOR  IN  PASTEURIZATION" 


(CIRCULAR   184— BUREAU    OF  ANIMAL   INDUSTRY)    U.   S.    DEPT.   OF 
AGRICULTURE. 


1=0 


Showing  the  Tagliabue  System  of  Au- 
tomatic Temperature  Control  applied 
to  a  Milk  Pasteurizer. 
Much  more  certain  than  hand  con- 
trol. By  means  of  this  system  and 
cleanliness  a  constantly  good  pro- 
duct is  the  sure  result. 
Write  for  full  information,  mention- 
ing make  of  your  Pasteurizer. 


.^j^^^^gt^ 


Boston 
Philadelphia 
Pittsburgh 
Cleveland 


C.  J.  TAGLIABUE   MFG.   CO 

IS  to  88  Thirty-Third  Street 

BROOKLYN,  NEW  YORK 


Chicago 

St.  Louis 

New  Orleans 

San  Francisco 


Condensed  Milk  and  Milk  Powder 


Tyc 


OS 


Automatic  Temperature  and  Pressure  Regulators 


Will   control   Temperature  in 

the  sterilizer  with  neglible 

variation. 
Tliousandis    beinig    used    daily 

fotr  miamy  applications. 
LOW   COST 

Practically  Indestructible. 


mK 


H&  JI 

Thermometer 


Thermometers  for  any  and 
all  applications.  Write  for 
catalog. 


Tycos    Recording  Thermometer. 

It   will   work    for   you    every    minute,   every    hour, 
every  day. 

If  the  temperature  does  vary  it  writes  it  all  down 
in  ink  for  you. 

It    is    doing    something    every    instant    and    you 
cannot  get  away  from  the  truth  it  tells. 

The  Tycos  Recording  Thermometer  is  made  for 
any  application  covering  temperature  ranges  from 
40°   below  0  to  1000°   above  0. 

It   operates   by  the   expansion   and   contraction   of 
mercury. 

Tycos 'Yime  Valve 

An  Automatic  Cooker 

It  does  its  work  completely. 
Shuts  off  steam  and  opens  the 
exhaust  automatically  and  simul- 
taneously at  just  the  right 
moment. 

ASK    FOR    FACTS  Recording 

Thermometer. 


The  HC^M  Division 

Taylor  Instrument  Companies 

Rochesten  N.Y 


Condensed  Milk  and  Mii,k  Powder 


259 


The  Engineering  Company 

Fort  Wayne,  Indiana 


We  build  Sterilizers  from  40  cases  per  charsre  to  270  cases  per  charge  and  all 
intermediate  sizes.  The  latest  scientUlt!  and  mechanical  ideas  are  embodied  in  this 
machine.  It  is  sanitary;  the  distribution  of  heat  is  absolute  and  under  full  control 
of  the  operator;  it  requires  less  operating  i)ou-er,  water  and  steam  than  any  other 
style  of  sterilizer;  it  saves  time  in  loading  and  unloading,  cannot  he  overbalanced, 
has  no  exposed  gears  and  runs  silently.  Our  shakers  are  constructed  with  a  wide 
range   of   capacity   and    are    giving   excellent   satisfaction. 

The  material  used  on  all  our  machines  is  the  very  best  that  money  can  purchase, 
and  with  our  organized  system  and  our  corps  of  first-class  mechanics,  we  are  well 
prepared  to  keep  abreast  of  any  new  improvements. 

THE  ENGINEERING  CO. 

Fort  Wayne,  Indiana 


260 


Condensed  Milk  and  Milk  Powder 


For  Sanitary  Service  Use 


tuMes 


^m 


/^-M 


They  are  easy  to  clean  and  keep  clean. 
The  most  sanitary,  and  the  most  econom- 
ically  operated    milk    plants    use   them    ex 

clusively. 

The)'   are  made  of   highest  quality  steel  plate, 
tinned  and  retinned.     All  seams  are  soldered 
on  the  inside  —  perfectly  smooth.     No  crev- 
ices for  milk  particles  to  lodge  in  and  sour. 
You  should  see  our  extra  heavy  seamless 
rim  cover. 

Sold  for  Calaloz  Ao.  111. 

Sturges  &  Bum  Mfg.  Co. 

508  South  Green  Street 

Chicago,  111. 


TORSION  BALANCE  CREAMERY  SCALES 


No  knife-ed^es — No  Friction — 

No  Wear 

Sensitive  and  Accurate 

No  loose  parts  to  shift.  Working  parts 
practically  in  one  piece. 

Torsion  Balance  four  bottle  Cream  Test  Scale 
Style  1530  is  mostly  used  by  collection 
stations,  creameries  and  milk  condenseries 
on  account  of  its  extreme  accuracy. 

Your  profits  depend  on  your  tests  as  much  as 
anything  else,  probably  more  so. 

The  Torsion  Balance  Company 

IMannfacturers  of  Special  Scales 
{or  Special  Purposes 


Style  No.  1530. 
Evaporated  Milk  Scale 

Factory  and  Works: 
147  9  Eighth  St. 
Jersey  City,  N.J. 


Pacific  Coast  Branch: 
50-52  California  St.. 
San  Francisco,  Cal. 


Office: 

92  Reade  St., 
New  York,  N.Y. 


Condensed  Milk  and  Milk  Powder 


261 


THE  WAGNER  PRECISION 
BABCOCK  GLASSWARE 


For  testiuEC  milk  and  its  products,  in  accord- 
ance with  specifications  formulated  by  tlie  Bureau 
of  Standards,  Washington,  D.  C,  U.  S.  A.,  March  2S. 
1911,  and  adopted  by  the  Official  Dairy  Instructors' 
Association,   October   30,    1911. 

In  a  circular  the  Bureau  of  Standards  has  set 
forth  all  -the  specifications  which  must  be  followed 
in  the  construction,  as  well  as  the  methods  to  be 
used  in  the  verifications  of  calibration.  These  speci- 
fications are  generally  known,  those  who  are  unac- 
quainted with  them  can  easily  obtain  a  circular  by 
applying  to  the   Bureau. 

We  only  desire  to  say  here  that  all  our  Preci- 
sion Glassware  is  made  in  strict  accordance  with 
the  specifications  of  the  Bureau  of  Standards.  In 
our  manufactories  in  New  York  City  and  Camden. 
X.  J.,  every  precaution  is  taken  to  produce  uni- 
formly excellent  ware,  very  clear,  free  from  striae, 
and  characterized  by  the  accuracy  and  perfection 
of   its   graduations. 

The  markings  are  Unusually  exact,  the  lines 
being  sharp  and  uniform.  The  per  cent  marks  on 
thd^Test  Bottles  and  pipettes  are  complete  circles, 
the  half  per  cent  marks  are  semi-circles,  while  all 
other  fractions  are  indicated  with  marks  which 
are  longer  than  those  usually  employed;  the  num- 
bers are  large,  even  and  distinct.  The  circled 
graduation  eliminates  all  former,  existing  errors  in 
reading  the  test,  the  operator  holds  the  bottle  in 
such  a  position  that  the  front  line  covers  the  back  1 
line;  in  other  words,  the  operator  must  hold  t 
bottle  perfectly  vertical  at  both  points  in  reading  I 
the  test.  All  markings  are  permanent,  and  when  | 
especially  ordered  may  be  filled  with  coloring  mat- 
ter. 

The  Wagner's  Precision  Glassware  has  gained  | 
its  popularity  because  of  its  distinctive  excellency 
and    reliability. 

We  manufacture  absolutely  accurate  Ther- 
nioiiieters,  Beaume  Hydrometers,  Lactometers,  and  | 
a  general  line  of  chemical  laboratory  glass  appa- 
ratus. 


THE    WAGNER    GLASS    WORKS 

695-697  E.  132d  St., 
NEW  YORK  CITY 


262 


Condensed  Milk  and  Milk  Powder 


Perfection  Brand  Butter  Color 

LAKTONE  AND  CHEESE  COLOR 

Both  Purely  Vegetable 

C.    T.   No.   2 — For  preserving  milk  samples  for  composite  testing. 
CLEARLINE — Facilitates  the  reading  of  tests.    Eliminates  the-meniscus. 

These  well  known  creamery  requisites  are  manufactured  by 
THE    PRESERVALINE    MFG.  CO.  Brooklyn,   New  York  City. 


GUARANTEED 

the  Most  Etfective 

Insulating  Material  for  Cold  Storage  rooms 

The  chemists  oi  this  company  have  recently 
by  tlie  use  o{  a  new  fibre  and  new  water- 
proofing, improved  the  strength  and  insula- 
ting quahties  of  Lith  until  it  now  is  superior 
to  all  others  for  insulating  work.  It  is  a 
combination  of  flax  fibres,  rock  fibre  wool 
and  a  waterproof  compound,  containing 
witliin  a  unit  volume  the  greatest  possible 
number  of  small  air  spaces.  Absolutely  no 
capillary  attraction  ;  clean  and  sanitary  ;  easy 
to  handle;  can  be  sawed  like  lumber.  Ideal 
insulation    for    milk    condenseries. 

Union  Cork  Board 


;  two  ingred 


pure  natu 


cork 


granulesand  a  specially  prepared  asphalti 
The  best  possible  insulation  for  floors  where 
^^        there  is  a  great  deal  of  moisture. 

OwofetT 

^■^Tho  Building  Quilt  for 
Houses  and  Barns 

Manufactured  of  chemically  treated  flax  fibres 
quilted  between  two  sheets  of  waterproof,  or 
strong  Kraft  paper.  Keeps  the  cold  or  heat 
from  entering.  Even  temperatures  all  year. 
Union  Fikre  Oompany,  107  Union  SI.,  Winona.  Minn. 


^t^l^^^tvUBWK** 


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